cppreference.com

Std::vector<t,allocator>:: insert.

Inserts elements at the specified location in the container.

If after the operation the new size() is greater than old capacity() a reallocation takes place, in which case all iterators (including the end() iterator) and all references to the elements are invalidated. Otherwise, only the iterators and references before the insertion point remain valid.

[ edit ] Parameters

[ edit ] return value, [ edit ] complexity, [ edit ] exceptions.

If an exception is thrown other than by

  • the copy constructor of T ,
  • the copy assignment operator of T ,
  • any InputIt operation,

these functions have no effect ( strong exception safety guarantee ).

[ edit ] Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

[ edit ] See also

  • Recent changes
  • Offline version
  • What links here
  • Related changes
  • Upload file
  • Special pages
  • Printable version
  • Permanent link
  • Page information
  • In other languages
  • This page was last modified on 9 August 2020, at 08:47.
  • This page has been accessed 1,458,477 times.
  • Privacy policy
  • About cppreference.com
  • Disclaimers

Powered by MediaWiki

  • <cassert> (assert.h)
  • <cctype> (ctype.h)
  • <cerrno> (errno.h)
  • C++11 <cfenv> (fenv.h)
  • <cfloat> (float.h)
  • C++11 <cinttypes> (inttypes.h)
  • <ciso646> (iso646.h)
  • <climits> (limits.h)
  • <clocale> (locale.h)
  • <cmath> (math.h)
  • <csetjmp> (setjmp.h)
  • <csignal> (signal.h)
  • <cstdarg> (stdarg.h)
  • C++11 <cstdbool> (stdbool.h)
  • <cstddef> (stddef.h)
  • C++11 <cstdint> (stdint.h)
  • <cstdio> (stdio.h)
  • <cstdlib> (stdlib.h)
  • <cstring> (string.h)
  • C++11 <ctgmath> (tgmath.h)
  • <ctime> (time.h)
  • C++11 <cuchar> (uchar.h)
  • <cwchar> (wchar.h)
  • <cwctype> (wctype.h)

Containers:

  • C++11 <array>
  • <deque>
  • C++11 <forward_list>
  • <list>
  • <map>
  • <queue>
  • <set>
  • <stack>
  • C++11 <unordered_map>
  • C++11 <unordered_set>
  • <vector>

Input/Output:

  • <fstream>
  • <iomanip>
  • <ios>
  • <iosfwd>
  • <iostream>
  • <istream>
  • <ostream>
  • <sstream>
  • <streambuf>

Multi-threading:

  • C++11 <atomic>
  • C++11 <condition_variable>
  • C++11 <future>
  • C++11 <mutex>
  • C++11 <thread>
  • <algorithm>
  • <bitset>
  • C++11 <chrono>
  • C++11 <codecvt>
  • <complex>
  • <exception>
  • <functional>
  • C++11 <initializer_list>
  • <iterator>
  • <limits>
  • <locale>
  • <memory>
  • <new>
  • <numeric>
  • C++11 <random>
  • C++11 <ratio>
  • C++11 <regex>
  • <stdexcept>
  • <string>
  • C++11 <system_error>
  • C++11 <tuple>
  • C++11 <type_traits>
  • C++11 <typeindex>
  • <typeinfo>
  • <utility>
  • <valarray>
  • vector<bool>
  • vector::~vector
  • vector::vector

member functions

  • vector::assign
  • vector::back
  • vector::begin
  • vector::capacity
  • C++11 vector::cbegin
  • C++11 vector::cend
  • vector::clear
  • C++11 vector::crbegin
  • C++11 vector::crend
  • C++11 vector::data
  • C++11 vector::emplace
  • C++11 vector::emplace_back
  • vector::empty
  • vector::end
  • vector::erase
  • vector::front
  • vector::get_allocator
  • vector::insert
  • vector::max_size
  • vector::operator[]
  • vector::operator=
  • vector::pop_back
  • vector::push_back
  • vector::rbegin
  • vector::rend
  • vector::reserve
  • vector::resize
  • C++11 vector::shrink_to_fit
  • vector::size
  • vector::swap

non-member overloads

  • relational operators (vector)
  • swap (vector)

std:: vector ::insert

Return value, iterator validity, exception safety.

Search anything:

Add elements to your vector using Vector::push_back() in C++

Software engineering c++ standard template library.

Internship at OpenGenus

Get this book -> Problems on Array: For Interviews and Competitive Programming

Reading time: 20 minutes | Coding time: 2 minutes

Vectors in C++ are one of the most used containers after arrays mainly because of the fact that the basis of operation of both the vectors and array are same to some extent.

In this article we will take a look into one of the most conventional ways of taking input in the vector as vector::push_back() and will try to find the complexity and other aspects in which it differs from the usual array implementation in taking the input.

One Major difference between array and vectors is their declaration type. std::Array is declared as array<class type, size_t Size> while Vector declaration is done using Allocator Policy , vector<class type, class Allocator=std::allocator<type> > This puts up the fact that the array size must be declared at the compile time while vector can be or not be allocated any predefined memory as it can resize the limits to ensure multiple objects at different contiguous memory locations.

Vectors in C++ are Containers . Containers are abstract Data type in C++ which acts as a way to store multiple objects and follow specific rules to access the elements.

There are multiple methods which can be applied to containers, which includes:

  • creating objects
  • accessing the elements
  • deleting the objects

Vector::push_back() method is used to insert elements at the back of the vector.

In C++11 and later standards the goto implementation of vector::push_back() has been reduced to providing/allocating data types at the compile time which is inserted at the back of the vector.

The general method for push_back() is:

while for c++11 and later standards it's :

Vector::push_back() for different data types:

Vector::push_back() for 2d vectors.

  • First way describes how to make a 2D vector and insert row and column wise elements:
  • Second way is more generic in nature. When we make the two vectors (the inner and the outer vector) by assigning values to one of them first and then declaring one vector as the part of the other:
  • Third Method can be described as the most naive way to take 2D vector input which is by simply taking input at the i-th column for each particular row:

Element access in 2D Vector

The most generic way is to iterate through each row and column to scrape the values present in the vector:

Time Complexity of a vector::push_back() operation

The complexity of the vector::push_back() operation is Amortized O(1).

What is amortized you may ask?

Simply said, Amortized complexity is basically the average of all the push_back() calls you would make in a vector in a particular range unit of time.

Any random push_back call will strictly be O(1) because we're essentially adding element at the end of the vector which is and can be done in constant time. But the moment the vector is empty or too small, (the vector.empty() check method can be used to proofcheck) the whole vector is reallocated and the time expense is usually O( vector.size() ).

Therefore at an average the time complexity increases and become Amortized O(1).

We can essentially limit the complexity to strictly O(1) by reserving the vector some space by std::reserve() .

Application of push_back.

The vector::push_back() call is an extremely inexpensive task and is widely used whenever vector container is used in general.

OpenGenus IQ: Computing Expertise & Legacy icon

  • [email protected]

insert vector 2d

What’s New ?

The Top 10 favtutor Features You Might Have Overlooked

FavTutor

  • Don’t have an account Yet? Sign Up

Remember me Forgot your password?

  • Already have an Account? Sign In

Lost your password? Please enter your email address. You will receive a link to create a new password.

Back to log-in

By Signing up for Favtutor, you agree to our Terms of Service & Privacy Policy.

2D Vectors in C++: Declaration, Operations & Traversal

  • Dec 08, 2022
  • 7 Minutes Read
  • By Anubhav Agarwal

2D Vectors in C++: Declaration, Operations & Traversal

We all are familiar with arrays in C++, but today in this article we are going to look at the array but with dynamic properties like 2D Vector. Yes! you already know what we are talking about. So, vectors are nothing but arrays with dynamic properties, and let's quickly dive into them. 

What is a Vector?

Vectors are dynamic arrays, whenever an element is inserted or deleted they can resize themselves automatically. Elements are stored at contiguous storage therefore iterators can be used to access and traverse.

Given below is the syntax to declare a 1D vector in C++ :

Syntax : 

Basic Operations in Vectors?

Let us check different operations on vectors that can be performed which are provided by the class vector .

Some basic operations are :

Example: 

What is a 2d vector.

Vector of Vectors is a 2D vector, it is nothing but a dynamic array in C++ means it has the ability to resize itself automatically, whenever we add or remove elements in it. Like a 2D array, it consists of rows and columns where each row is a different type of vector. 

In order to use vectors in our program, we must include the vector header file provided by the Standard Template Library :

#include<vector>

Also, to include all kinds of Standard Template Libraries (STL) at once, we can use :

#include<bits/stdc++.h>

How to declare a 2D vector in C++?

Given below is the syntax to declare a 2D vector in C++ :

Syntax  : 

How to Initialize a 2D vector in C++?

There are various ways to initialize a 2D vector in C++.

Method 01) Using the above syntax.

Method 02) Initializing a 2D vector with vectors as elements inside it.

Method 03) Initializing a 2D vector where each row has values associated with them as defined by the user.

Method 04) Initializing a 2D vector of size 'n' rows and 'm' columns with all element values as 1.

Some Operations On 2D Vectors

Insertion: using push_back() function .

Example 1 :

Suppose we have a vector of vectors v1 and I want to push vector v2 = {4,5,6} inside it. Then,

v1.push_back(v2);

(This will push the v2 vector into the vector of vectors v1).

Now v1 becomes : v1 = {{4,5,6}}.

Example 2:     

Now, I want to push vector v3 in the above-created vector of vector v1. Then, (v3 = {1,2,3})

v1.push_back(v3); 

This will result in :

v1 = {{4,5,6},{1,2,3}}

Below is the C++ program to demonstrate the above :

Deletion or Removal: Using pop_back() function

Below is the C++ program to show how to perform deletion in a 2D vector using the pop_back() function:

How to traverse in a 2D vector?

Below is the C++ program to show how to traverse in a 2D vector using iterators :

Problems related to matrices, graphs, and other two-dimensional objects involve using 2D vectors to the great extent. So it is very crucial to have a deep understanding of how to declare, initialize, traverse, insert and remove elements in or from a 2D vector.

I hope this article helped you to understand 2D vectors in C++ step by step. Keep Learning!

insert vector 2d

FavTutor - 24x7 Live Coding Help from Expert Tutors!

insert vector 2d

About The Author

insert vector 2d

Anubhav Agarwal

More by favtutor blogs, correlated subquery in sql explained, tanish mallik.

insert vector 2d

RANK() and DENSE_RANK() Functions in SQL

insert vector 2d

What does $ mean in R? (How to Use?)

Aarthi juryala.

insert vector 2d

2D Vector in C++

C++ Course: Learn the Essentials

In C++, 2D vectors, or 'vectors of vectors,' act like dynamic matrices. They efficiently store elements in contiguous spaces, allowing variable sizes and easy access. Essential for creating flexible structures, 2D vectors differ from single-dimensional ones in their ability to dynamically resize and hold multiple vectors.

Including the Vector Header File

The C++ Standard Template Library includes vectors. We must include the vector header file in our program to use vectors.

Instead of including numerous kinds of Standard Template Libraries (STL) one by one, we can include all of them by:

Initializing a 2D Vector in C++

Let's say you want to initialize a 2D vector, m * n , with the initial value to be 0 .

We could do this :

  • Declaration :

The above code produces a 2D vector that is empty. Before using it, we must set the vector size and provide space for its components. The fill function constructor, the resize() and push_back() methods, and other techniques can all be used to build a two-dimensional vector.

  • Making use of Fill Constructor For initializing a two-dimensional vector, it is advised to utilize a fill function constructor.  The fill function constructor creates a vector with the required number of elements, and the value specified is filled into it.

Two stages can be used to break down the initialization described above: Create an int vector and initialize it with a default value before using it to create the two-dimensional vector. As an illustration, consider the following:

  • Use of the resize() method:

Here are two implementations that utilize an overloaded version of the resize() function that accepts two arguments: the size of the container and the object to be copied:

To resize a vector to the desired size, use the resize() function. It can be used to set a default value for a two-dimensional vector, as demonstrated below:

Remember that the preceding code may run worse when M and N are large due to the push_back() function's propensity to reallocate memory frequently. Therefore, push_back() should only be utilized when vector dimensions are unknown in advance.

  • Making use of Initializer Lists Finally, as illustrated below, we can initialize a two-dimensional vector with an assigned default value using initializer lists. Please take note that only C++11 and higher support this.

Specifying the Size for 2D Vector Initialization

The 2D vector can be initialized with a user-defined size as well. It is similar to using the new operator or malloc() to create a 2D dynamic array. Consequently, if we want to establish a 2D vector to rows n and columns m , we must start a 2D vector of size n with elements from a 1D vector of size m. We may accomplish that by following the steps below. The 2D array's values are default set to 0 .

As previously stated, A 2D vector is a vector of a 1D vector.

Let's think about the upper use case precisely like a 1D vector.

The outer vector is, therefore, of size n(number of rows).

The memory allocation function, or malloc() , dynamically allocates a memory block. It returns the null pointer, which corresponds to the memory address and reserves the memory space for the provided size.

Let's define that,

Now T is itself a 1D vector and has the size of m

Thus the element of the outer vector would be vector<int>v(m)

This combining,

The use of iterators is mentioned below in the article.

The outer loop iterates over all the rows of the 2D vector. The inner loop then iterates over the elements of this vector.

In the code above, we adhere to two conventions for initialization :

The string " vector<int> row(numcol, 0) " - In this expression, a single-dimensional vector named "row" is created. Its length is determined by the variable "num_col," and its default values are " 0 ." Our two-dimensional vector's rows are essentially formed by it. ' vector<vector<int>> v(num_row, row) ' and by identifying each value of the two-dimensional vector as a "row" produced in the previous sentence, we can create our entire two-dimensional vector in this statement.

After comprehending the aforementioned process, we can enhance the way we initialize 2D vectors in C++ by:

Since we are performing the same action in the aforementioned code, it will produce results similar to those obtained previously.

If memory serves, the standard startup resembles the one shown above. To create a two-dimensional vector, we must make every element's default value a single-dimensional vector.

The final technique entails building a 2D vector without understanding rows or columns. It's completed by:

The declaration in the above sentence establishes an empty container that can hold elements in the form of vectors.

Iterators for 2D Vectors

  • Use range-based for loops to iterate through a vector in C++ .

In C++11, range-based for loops were first made available. A more understandable way of looping over a container is helpful. Let's examine how we can iterate over an array of integers using this range-based for loops and print each entry as we go.

Here, we iterated over all the vector's components, using the auto type to choose each. The advantage of this strategy is that the type of the vector's elements need not be specified. Additionally, we may perform various operations with each element in addition to printing them.

  • Utilize indexing to iterate over a vector in C++. We iterated through each element in the vector in the preceding example. However, we were unaware of the index positions of the components during iteration. Therefore, we can use the standard for loop to iterate through all of a vector's elements by indexing. For instance, Iterate over a vector in C++ using indexing.

In the previous example, we iterated over all items in vector. But during iteration, we were not aware of the index positions of the elements. So, if we want to iterate over all vector elements through indexing, we can use the normal for loop. For example,

  • C++: Iterate over a vector using Iterators

For each unique STL data structure, C++ offers iterators as an alternative to utilizing indices to navigate a 2D vector.

The iterators are useful when we employ specific operations that call for a positional argument. The top two functions that return iterator values are:

  • v.begin() - This function returns an iterator that goes to the first vector in a 2-D vector.
  • v.end() - returns an iterator that iterates across the 2-D vector until its end.
  • C++: Iterate over a vector in a single line We can loop over every element of a vector in a single line by using the STL Algorithm for_each(start, end, callback) . It will take three arguments: an Iterator pointing to the start of a range, also known as a start iterator, an iterator pointing to the end of a range, known as an end iterator, and a callback function discussed below.

Callback Function: A function that must be applied to each element in the range, starting at the beginning and ending at the end. Between start and end iterators, all the elements are iterated over for_each() , which applies the specified callback to each element. We can supply the for_each method with iterators pointing to the beginning and end of the vector. It goes through every element of the vector and applies the lambda function supplied to each one.

Several built-in functions in the algorithm library offer a range of functionalities (e.g., sorting, searching, counting, modifying, and non-modifying sequence operations). These functions can all be applied to a variety of elements.

Let’s see an example,

Here, we applied a lambda function to each vector element and printed each element inside the lambda function.

C++ Lambda expression allows us to define anonymous function objects (functors), which can either be used inline or passed as an argument.

Adding Elements to a 2-D Vector

The C++ STL's push_back() method can be used to insert elements into a vector.

The insertion operation in a vector of vectors is shown in the example below. The push_back() function is used in the code to construct a 2D vector displayed alongside the matrix.

Time complexity is O(1).

Methods used to remove elements from vector are:

  • vector_name.push_back(value)

Where value refers to the element added to the vector's back.

This function pushes vector v2 into a vector of vectors v1 . Therefore v1 becomes { {3, 5, 6, 7} } .

Since it is a vector of vectors, it would only make sense to push full vectors into our container. Therefore, the" push_back() " function requires a vector as an input.

' v[i] ' represents a single-dimensional vector. Therefore, if the programmer needs to add elements in a certain vector inside the 2-D vector, he may use ' v[i].push_back(value) '

  • Use the " insert() " function to add a full vector at a given point as shown here:

Instead of an integral index, the insert() function requires a positional input as an iterator. A vector meant to be put at the designated point follows it.

Time complexity is O(N + M) where N is the number of elements inserted and M is the number of elements moved.

Removing Elements From 2D Vectors in C++

  • vector::pop back() The method vector::pop back() removes elements from a vector. It eliminates the removed element and shrinks the container by one.

Exceptions and Errors:

  • No-Throw Guarantee: The container remains unchanged if an exception is thrown.
  • If a vector is empty, it behaves undefinably.

Does pop_back() eliminate values in addition to elements? The last element is eliminated when this method is called. The object's destructor is invoked, and the vector's length is reduced by 1.

Time Complexity: O(1) or (Amortized constant)

  • vector::pop_front() There is no inbuilt function, pop_front(), for vectors, but it can be implemented on our own. We have to remove the first element, and since the rest of the elements needs to be shifted by one index to the left, the time complexity is linear. Time Complexity: O(N) Syntax:

Complete example:

  • vector::erase(): Removes either a single element or a range of elements.

Time Complexity: O(N) - worst case

An example of erase method is:

Traversing the Entire Matrix Created Using a 2D Vector

There are two ways to move about in a matrix. Row-wise traversal goes over each row one at a time, starting with the first row, moving on to the second, and so on till the last row. From index 0 to the last index, elements from the row are returned.

Elements are traversed sequentially from the first to the last column using a column-wise traversal method.

M is a 2D matrix. Columns are represented by index j, while rows are represented by index i.

  • For row-wise traversal, start from
  • For column-wise traversal, start from

The order of indexes remains the same in the 2D array M[i][j]- i for rows and j for columns .

If we run the above code, it will generate the following Output:

  • Traversing diagonally: Given a 2D matrix, print all elements of the given matrix in a diagonal order. For example, consider the following 5 X 4 input matrix.

Traversing diagonally

Diagonal printing of the above matrix is:

Implementation:

  • In C++ programming, data organized into rows and columns is stored and accessed using a 2D vector.
  • When using 2D vectors in C++, a programmer needs to know the necessary syntax.
  • The C++ vectors data structure not only functions as a dynamic array but also guarantees speedy and random access to the components of that vector. Now, you can efficiently manage computer memory while easily adding, deleting, traversing, and modifying vectors' elements.
  • The vector size can be changed by adding or removing components from the vector used to build a dynamic array. A 2D vector functions similarly to a 2D array and is defined inside another vector.
  • The foundation for dynamically constructing matrices, tables, and other structures is 2D vectors in C++.
  • A 1D vector can be created, and then all of the one-dimensional vectors are pushed as elements into a 2D and have the option to push back both empty and partially filled vectors.
  • The row-major-order and column-major-order traversals of matrices are two popular approaches. When a matrix is accessed row by row, it is in row-major order. When a matrix is accessed column by column, it is in column-major order.
  • Auto in C++ .

How to Append Vector to Vector in C++

  • How to Append Vector to Vector in C++

Append a Vector to Another Vector in C++ Using the insert Function

Append a vector to another vector in c++ using the std::copy algorithm, append a vector to another vector in c++ using a range-based loop.

How to Append Vector to Vector in C++

C++ provides a versatile and efficient standard template library (STL) that includes a powerful container called a vector. Vectors are dynamic arrays that can be resized dynamically, making them a popular choice for managing collections of elements.

In certain scenarios, you might need to append the contents of one vector to another. This article will explain several methods of how to append a vector to another vector in C++.

The insert function provides an efficient way to append the contents of one vector to another in C++. The insert function is part of the std::vector container and allows us to add elements from one vector to another at a specified position.

Syntax of the insert Function:

  • pos : Iterator pointing to the position where elements will be inserted.
  • value : The element or value to be inserted.
  • count : Number of elements to insert.
  • first and last : Range of elements to insert.

The insert function takes an iterator position and a range of elements to insert. By specifying the end iterator of the source vector as the range, we can effectively append the entire vector.

Example 1: Appending Vectors Using the insert Function

Let’s consider a scenario where we have two integer vectors, i_vec1 and i_vec2 , and we want to append the elements of i_vec2 to the end of i_vec1 .

In this example, initially, two vectors, i_vec1 with elements {1, 2, 3} and i_vec2 with elements {4, 5, 6} , are defined. The insert function is then employed to append the entire range of i_vec2 to the end of i_vec1 by specifying iterators as arguments.

Finally, the result is displayed by iterating through the combined vector ( i_vec1 ) using a range-based for loop.

Appending Vectors Using insert

Example 2: Generic Approach Using the std::end and the std::begin Functions

A more generic approach involves using std::end and std::begin to specify iterators, allowing flexibility in passing arguments to the insert function.

This example builds upon the previous one but adopts a more generic approach by using the std::end and std::begin functions to obtain iterators. The vectors i_vec1 and i_vec2 are the same as in Example 1.

The insert function is applied to append the elements of i_vec2 to the end of i_vec1 . However, instead of explicitly using i_vec1.end() , std::end(i_vec1) is employed for enhanced generality.

The output, displayed using a range-based for loop, remains identical to Example 1.

Appending Vectors Using insert - Generic Approach

Example 3: Adding Elements With a Specified Value

The insert function can also be used to add a range of elements with a given value at a specified position in the vector.

In this example, the integer vector i_vec is initially defined with elements {1, 2, 3, 4, 5} . The insert function is applied with i_vec.begin() specifying the insertion position and 4 indicating the count of zeros to be added.

The output, obtained by iterating through the modified vector, reveals the following result.

Appending Vectors Using insert - Add Elements with a Specified Value

Example 4: Concatenating String Vectors

The insert function is versatile and can also be applied to concatenate vectors of different types, such as strings.

Here, two string vectors, str_vec1 with elements {"apple", "orange"} and str_vec2 with elements {"banana", "grape"} , are defined. Using the str_vec1.end() as the insertion point and str_vec2.begin() with the str_vec2.end() as the range, the insert function seamlessly combines the string vectors.

The output is also displayed using a range-based for loop.

Concatenating String Vectors Using insert

The insert function in C++ provides a flexible and efficient way to append vectors. Whether you’re merging numeric vectors, adding elements with a specific value, or concatenating vectors of different types, the insert function simplifies the process, enhancing code readability and maintainability.

In C++, the std::copy algorithm provides an alternative and concise way to append one vector to another. This algorithm is part of the <algorithm> header and offers a straightforward approach to copying elements from one range to another.

Syntax of the std::copy Algorithm:

  • first and last : Define the range of elements to copy.
  • d_first : Iterator pointing to the beginning of the destination range.

Example 1: Appending Vectors Using the std::copy Function

In this example, we have two integer vectors, i_vec1 and i_vec2 , initially containing {1, 2, 3} and {4, 5, 6} , respectively. The goal is to append the elements of i_vec2 to the end of i_vec1 using the std::copy algorithm.

In this example, the std::copy algorithm is applied to copy the elements from the range defined by i_vec2.begin() and i_vec2.end() to the end of i_vec1 .

The back_inserter function ensures that the elements are appended to the destination vector ( i_vec1 ). The final output demonstrates the successful appending of vectors.

Appending Vectors Using std::copy

Example 2: Concatenating String Vectors

This example showcases the versatility of the std::copy algorithm by concatenating two vectors of strings, str_vec1 and str_vec2 .

Here, the std::copy algorithm efficiently concatenates the string vectors. The back_inserter function ensures that the elements from str_vec2 are appended to the end of str_vec1 .

The output reflects the successful concatenation of the string vectors.

Appending String Vectors Using std::copy

Example 3: Generic Approach With Different Data Types

The std::copy algorithm can seamlessly handle vectors of different data types, as demonstrated in this example.

Here, we illustrate the generic capability of the std::copy algorithm to handle vectors with different data types. Two vectors, int_vec with integer elements and double_vec with double elements, are used.

The copy function appends the elements of double_vec to the end of int_vec using the back_inserter function. The output, displayed using a for loop, shows the successfully appended vector, highlighting the algorithm’s ability to handle different data types seamlessly.

Appending Vectors Using std::copy - Generic Approach

The std::copy algorithm provides a concise and flexible way to append one vector to another in C++. Its simplicity and compatibility with various data types make it a versatile choice for copying and concatenating vectors.

In C++, a range-based loop provides a concise and readable way to iterate through the elements of a container. Leveraging this loop structure, we can easily append one vector to another.

Syntax of a Range-Based Loop:

  • source_vector : The vector from which elements are extracted.
  • destination_vector : The vector to which elements are appended.

Example: Appending Vectors Using a Range-Based Loop

In this example, we have two integer vectors, i_vec1 and i_vec2 , initialized with values {1, 2, 3} and {4, 5, 6} , respectively. The objective is to append the elements of i_vec2 to the end of i_vec1 using a range-based loop.

In this C++ code snippet, we use the loop syntax for (const auto& element : i_vec2) to iterate through each element in i_vec2 . For each iteration, we use the push_back method to append the current element to the end of i_vec1 .

This loop effectively appends all elements of i_vec2 to the end of i_vec1 .

Following the range-based loop, we proceed to display the result. Another range-based loop is used to iterate through the elements of the modified i_vec1 , and the cout statement prints each element followed by a space.

The final output, displayed in the console, demonstrates the successful appending of vectors.

Appending Vectors Using a Range-Based Loop

A range-based loop provides a clean and straightforward approach to append one vector to another in C++. The concise syntax enhances code readability, and its simplicity makes it an appealing choice for appending vectors.

Appending one vector to another in C++ can be achieved through various methods, each offering its advantages.

The insert function, a versatile tool within the std::vector container, provides flexibility for merging vectors by specifying insertion points and ranges. The std::copy algorithm simplifies the process, offering a concise and readable solution for copying elements from one vector to another.

Additionally, the use of a range-based loop provides an elegant and straightforward way to iterate through elements and append vectors seamlessly. Whether you choose the insert function, std::copy algorithm, or a range-based loop, the key lies in selecting the approach that aligns best with your code style and specific requirements.

With these methods at your disposal, you have the tools to efficiently modify and concatenate vectors in C++, enhancing the flexibility and readability of your code.

Jinku Hu avatar

Founder of DelftStack.com. Jinku has worked in the robotics and automotive industries for over 8 years. He sharpened his coding skills when he needed to do the automatic testing, data collection from remote servers and report creation from the endurance test. He is from an electrical/electronics engineering background but has expanded his interest to embedded electronics, embedded programming and front-/back-end programming.

Related Article - C++ Vector

  • How to Iterate Through a Vector in C++
  • Vector Iterator in C++
  • How to Resize 2D Vector C++
  • How to Calculate Angle Between Two Vectors in C++
  • How to Deallocate a std::vector Object in C++
  • Multidimensional Vectors in C++

numpy.insert #

Insert values along the given axis before the given indices.

Input array.

Object that defines the index or indices before which values is inserted.

New in version 1.8.0.

Support for multiple insertions when obj is a single scalar or a sequence with one element (similar to calling insert multiple times).

Values to insert into arr . If the type of values is different from that of arr , values is converted to the type of arr . values should be shaped so that arr[...,obj,...] = values is legal.

Axis along which to insert values . If axis is None then arr is flattened first.

A copy of arr with values inserted. Note that insert does not occur in-place: a new array is returned. If axis is None, out is a flattened array.

Append elements at the end of an array.

Join a sequence of arrays along an existing axis.

Delete elements from an array.

Note that for higher dimensional inserts obj=0 behaves very different from obj=[0] just like arr[:,0,:] = values is different from arr[:,[0],:] = values .

Difference between sequence and scalars:

C++ STL – Full Course

insert vector 2d

Insert Element at Specific index in Vector in C++

In this article we will discuss how to insert one or multiple elements at specific index in vector.

Vector provides different overloaded version of member function insert() , to insert one or more elements in between existing elements. Let’s discuss them in detail,

Inserting a single element at specific position in vector

We are going to use first overloaded version of Vector’s insert() function i.e.

It Inserts a copy of give element “val” , before the iterator position “ pos ” and also returns the iterator pointing to new inserted element.

Let’s understand by example,

Suppose we have a vector of int i.e.

Now we want to insert an element at index position 4th (In vector position index start from 0),

Vector’s contents will be now,

Inserting an element in vector will increase the vector size by 1. As in vector all elements are stored at continuous memory locations, so inserting an element in between will cause all the elements in right to shift or complete reallocation of all elements.

Inserting multiple elements or a range at specific position in vector

Some times we encounter a situation where we want to insert multiple elements in vector at specific position. These multiple elements can from another vector , array or any other container.

For this, vector provides an overloaded version of insert() function to insert multiple elements i.e.

It inserts the elements in range from [first, end) before iterator position pos and returns the iterator pointing to position first newly added element.

Let’s understand by an example,

Suppose we have 2 vectors of strings i.e.

Now insert all the elements in vec2 at position 3 in vec1 i.e.

Contents of vec1 will be now,

Inserting multiple elements using Initializer list

Another overloaded version of vector’s insert() function is as follows,

It copies all the elements in given initializer list before given iterator position pos and also returns the iterator of first of the newly added elements.

Suppose we have vector of int i.e.

Let’s add all elements in initialisation list to the existing vector i.e.

Contents of vecOfInts will be now,

vector.insert() and Iterator invalidation

Inserting elements in vector will cause existing elements to shift places or sometimes complete reallocation, which will invalidates all the existing iterators.

Complete example is as follows,

To Compile the above example in linux use following command,

g++ –std=c++11 example.cpp

To provide the best experiences, we and our partners use technologies like cookies to store and/or access device information. Consenting to these technologies will allow us and our partners to process personal data such as browsing behavior or unique IDs on this site and show (non-) personalized ads. Not consenting or withdrawing consent, may adversely affect certain features and functions.

Click below to consent to the above or make granular choices. Your choices will be applied to this site only. You can change your settings at any time, including withdrawing your consent, by using the toggles on the Cookie Policy, or by clicking on the manage consent button at the bottom of the screen.

  • C++ Data Types
  • C++ Input/Output
  • C++ Pointers
  • C++ Interview Questions
  • C++ Programs
  • C++ Cheatsheet
  • C++ Projects
  • C++ Exception Handling
  • C++ Memory Management

Related Articles

  • Solve Coding Problems
  • Implementation of lower_bound() and upper_bound() in Vector of Pairs in C++
  • Vector of Vectors in C++ STL with Examples
  • How does a vector work in C++?
  • Sorting Vector of Pairs by 1st element in ascending and 2nd element in descending
  • How to find the sum of elements of a Vector using STL in C++?
  • 2D Vector In C++ With User Defined Size
  • Implementation of lower_bound and upper_bound on Set of Pairs in C++
  • Initialize a vector in C++ (7 different ways)
  • vector :: cbegin() and vector :: cend() in C++ STL
  • vector::begin() and vector::end() in C++ STL
  • Keep track of previous indexes after sorting a vector in C++ STL
  • Sorting 2D Vector of Pairs in C++
  • Implementation of lower_bound() and upper_bound() in List of Pairs in C++
  • Get first and last elements from Array and Vector in CPP
  • Computing Index Using Pointers Returned By STL Functions in C++
  • How to erase an element from a vector using erase() and reverse_iterator?
  • vector::operator= and vector::operator[ ] in C++ STL
  • How to find index of a given element in a Vector in C++
  • Map of pairs in STL

2D Vector of Pairs in C++ with Examples

What is Vector?

In C++ , a vector is similar to dynamic arrays with the ability to resize itself automatically. Vector elements are stored in contiguous memory locations so that they can be accessed and traversed using iterators.

Some of the functions associated with a vector:

  • begin() : Returns an iterator pointing to the first element in the vector. Complexity-O(1).
  • end() : Returns an iterator pointing to the theoretical element that follows the last element in the vector. Complexity-O(1).
  • rbegin() : Returns a reverse iterator pointing to the last element in the vector (reverse beginning). It moves from last to first element. Complexity-O(1).
  • size() : Returns the number of elements in the vector. Complexity-O(1).
  • empty() : Returns whether the vector is empty. Complexity-O(1).
  • push_back() : It pushes the elements into a vector from the back. Complexity-O(1).
  • pop_back() : It is used to pop or remove elements from a vector from the back. Complexity-O(1).
  • insert() : It inserts new elements before the element at the specified position. Complexity-O(1).

What is 2D vector?

In C++, a 2D vector is a vector of vectors which means that each element of a 2D vector is a vector itself. It is the same as a matrix implemented with the help of vectors.

Some of the functions associated with a 2D vector:

  • size(): Returns the number of elements in the 2D vector. 
  • empty(): Returns whether the 2D vector is empty.
  • push_back(): It pushes a vector into a 2D vector from the back.
  • pop_back(): It is used to pop or remove elements from a 2D vector from the back.

What is Pair?

Utility header in C++ provides us pair container. A pair consists of two data elements or objects.

  • The first element is referenced as ‘first’ and the second element as ‘second’ and the order is fixed (first, second).
  • Pair is used to combine together two values that may be different in type. Pair provides a way to store two heterogeneous objects as a single unit.
  • Pair can be assigned, copied, and compared. The array of objects allocated in a map or hash_map is of type ‘pair’ by default in which all the ‘first’ elements are unique keys associated with their ‘second’ value objects.
  • To access the elements, we use variable name followed by dot operator followed by the keyword first or second.

How to access a Pair?

To access elements of a pair use the dot (.) operator.

auto fistElement = myPair.first; auto fistElement = myPair.second;

2D Vector of Pairs

A 2D vector of pairs or vector of vectors of pairs is a vector in which each element is a vector of pairs itself. 

vector<vector<pair<dataType1, dataType2>> myContainer Here, dataType1 and dataType2 can be similar or dissimilar data types.

Example 1: In the below C++ program, a vector of vectors of pairs of type {int, string} is used.

[  {0 , GeeksforGeeks}  {1 , GFG}  {2 , Computer Science}  ] [  {0 , C#}  {1 , C}  {2 , C++}  ] [  {0 , HTML}  {1 , CSS}  {2 , Javascript}  ] [  {0 , R}  {1 , Swift}  {2 , Python}  ]

Example 2: In the below C++ program, a vector of vectors of pairs of type {char, bool} is used.

[  {G , 0}  {e , 0}  {e , 0}  {k , 0}  ] [  {G , 1}  {e , 1}  {e , 1}  {k , 1}  ] [  {G , 0}  {e , 0}  {e , 0}  {k , 1}  ] [  {G , 0}  {e , 1}  {e , 0}  {k , 1}  ]

Time Complexity: O(N*M) where N is the size of the vector and M is the size of the pair.

Auxiliary Space: O(M)

Please Login to comment...

author

  • surinderdawra388

Improve your Coding Skills with Practice

 alt=

What kind of Experience do you want to share?

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

  • View all journals
  • Explore content
  • About the journal
  • Publish with us
  • Sign up for alerts
  • Published: 16 February 2024

Inverse-designed low-index-contrast structures on a silicon photonics platform for vector–matrix multiplication

  • Vahid Nikkhah   ORCID: orcid.org/0000-0003-0666-2614 1 ,
  • Ali Pirmoradi   ORCID: orcid.org/0009-0007-4653-8470 1 ,
  • Farshid Ashtiani   ORCID: orcid.org/0000-0002-8418-9626 1 , 2 ,
  • Brian Edwards   ORCID: orcid.org/0000-0001-9354-125X 1 ,
  • Firooz Aflatouni   ORCID: orcid.org/0000-0001-9314-2486 1 &
  • Nader Engheta   ORCID: orcid.org/0000-0003-3219-9520 1  

Nature Photonics ( 2024 ) Cite this article

346 Accesses

201 Altmetric

Metrics details

  • Metamaterials
  • Nanophotonics and plasmonics

Inverse-designed silicon photonic metastructures offer an efficient platform to perform analogue computations with electromagnetic waves. However, due to computational difficulties, scaling up these metastructures to handle a large number of data channels is not trivial. Furthermore, a typical inverse-design procedure is limited to a small computational domain and therefore tends to employ resonant features to achieve its objectives. This results in structures that are narrow-bandwidth and highly sensitive to fabrication errors. Here we employ a two-dimensional (2D) inverse-design method based on the effective index approximation with a low-index contrast constraint. This results in compact amorphous lens systems that are generally feed-forward and low-resonance. We designed and experimentally demonstrated a vector–matrix product for a 2 × 2 matrix and a 3 × 3 matrix. We also designed a 10 × 10 matrix using the proposed 2D computational method. These examples demonstrate that these techniques have the potential to enable larger-scale wave-based analogue computing platforms.

This is a preview of subscription content, access via your institution

Access options

Access Nature and 54 other Nature Portfolio journals

Get Nature+, our best-value online-access subscription

24,99 € / 30 days

cancel any time

Subscribe to this journal

Receive 12 print issues and online access

195,33 € per year

only 16,28 € per issue

Rent or buy this article

Prices vary by article type

Prices may be subject to local taxes which are calculated during checkout

insert vector 2d

Data availability

Data for Figs. 2 – 4 are available via Zenodo at https://doi.org/10.5281/zenodo.10083901 (ref. 39 ).

Code availability

All codes produced during this research are available from the corresponding author upon reasonable request.

Cordaro, A. et al. Solving integral equations in free-space with inverse-designed ultrathin optical metagratings. Nat. Nanotechnol. 18 , 365–372 (2023).

Article   ADS   CAS   PubMed   Google Scholar  

Nikkhah, V., Tzarouchis, D. C., Hoorfar, A. & Engheta, N. Inverse-designed metastructures together with reconfigurable couplers to compute forward scattering. ACS Photonics 10 , 977–985 (2022).

Google Scholar  

Silva, A. et al. Performing mathematical operations with metamaterials. Science 343 , 160–163 (2014).

Article   ADS   MathSciNet   CAS   PubMed   Google Scholar  

Mohammadi Estakhri, N., Edwards, B. & Engheta, N. Inverse-designed metastructures that solve equations. Science 363 , 1333–1338 (2019).

Zhang, H. et al. An optical neural chip for implementing complex-valued neural network. Nat. Commun. 12 , 457 (2021).

Article   ADS   CAS   PubMed   PubMed Central   Google Scholar  

Camacho, M., Edwards, B. & Engheta, N. A single inverse-designed photonic structure that performs parallel computing. Nat. Commun. 12 , 1466 (2021).

Fu, W. et al. Ultracompact meta-imagers for arbitrary all-optical convolution. Light Sci. Appl. 11 , 62 (2022).

Pan, D. et al. Laplace metasurfaces for optical analog computing based on quasi-bound states in the continuum. Photon. Res. 9 , 1758–1766 (2021).

Article   Google Scholar  

Zangeneh-Nejad, F., Sounas, D. L., Alù, A. & Fleury, R. Analogue computing with metamaterials. Nat. Rev. Mater. 6 , 207–225 (2021).

Article   ADS   Google Scholar  

Zhu, T. et al. Plasmonic computing of spatial differentiation. Nat. Commun. 8 , 15391 (2017).

Pors, A., Nielsen, M. G. & Bozhevolnyi, S. I. Analog computing using reflective plasmonic metasurfaces. Nano Lett. 15 , 791–797 (2015).

Wang, H. et al. Design of compact meta-crystal slab for general optical convolution. ACS Photonics 9 , 1358–1365 (2022).

Article   MathSciNet   CAS   Google Scholar  

Choutagunta, K., Roberts, I., Miller, D. A. & Kahn, J. M. Adapting Mach–Zehnder mesh equalizers in direct-detection mode-division-multiplexed links. J. Light. Technol. 38 , 723–735 (2019).

Knill, E., Laflamme, R. & Milburn, G. J. A scheme for efficient quantum computation with linear optics. Nature 409 , 46–52 (2001).

Nikkhah, V., Mencagli, M. J. & Engheta, N. Reconfigurable nonlinear optical element using tunable couplers and inverse-designed structure. Nanophotonics 12 , 3019–3027 (2023).

Article   CAS   Google Scholar  

Wang, T. et al. An optical neural network using less than 1 photon per multiplication. Nat. Commun. 13 , 123 (2022).

Shastri, B. J. et al. Photonics for artificial intelligence and neuromorphic computing. Nat. Photon. 15 , 102–114 (2021).

Article   ADS   CAS   Google Scholar  

Shen, Y. et al. Deep learning with coherent nanophotonic circuits. Nat. Photon. 11 , 441–446 (2017).

Lin, X. et al. All-optical machine learning using diffractive deep neural networks. Science 361 , 1004–1008 (2018).

Feldmann, J. et al. Parallel convolutional processing using an integrated photonic tensor core. Nature 589 , 52–58 (2021).

Wang, H., Guo, C., Zhao, Z. & Fan, S. Compact incoherent image differentiation with nanophotonic structures. ACS Photonics 7 , 338–343 (2020).

Zhu, T. et al. Topological optical differentiator. Nat. Commun. 12 , 680 (2021).

Goh, H. & Alù, A. Nonlocal scatterer for compact wave-based analog computing. Phys. Rev. Lett. 128 , 073201 (2022).

Farhat, N. H. Photonic neural networks and learning machines. IEEE Expert 7 , 63–72 (1992).

Wetzstein, G. et al. Inference in artificial intelligence with deep optics and photonics. Nature 588 , 39–47 (2020).

Miller, D. A. Self-configuring universal linear optical component. Photon. Res. 1 , 1–15 (2013).

Bogaerts, W. et al. Programmable photonic circuits. Nature 586 , 207–216 (2020).

Clements, W. R., Humphreys, P. C., Metcalf, B. J., Kolthammer, W. S. & Walmsley, I. A. Optimal design for universal multiport interferometers. Optica 3 , 1460–1465 (2016).

Tzarouchis, D. C., Mencagli, M. J., Edwards, B. & Engheta, N. Mathematical operations and equation solving with reconfigurable metadevices. Light Sci. Appl. 11 , 263 (2022).

Bendsoe, M. P. & Sigmund, O. Topology Optimization : Theory , Methods and Applications (Springer, 2004).

Molesky, S. et al. Inverse design in nanophotonics. Nat. Photon. 12 , 659–670 (2018).

Hughes, T. W., Minkov, M., Williamson, I. A. & Fan, S. Adjoint method and inverse design for nonlinear nanophotonic devices. ACS Photonics 5 , 4781–4787 (2018).

Hammer, M. & Ivanova, O. V. Effective index approximations of photonic crystal slabs: a 2-to-1-D assessment. Opt. Quantum Electron. 41 , 267–283 (2009).

Knox, R. & Toulios, P. Integrated circuits for the millimeter through optical frequency range. Proc. Symp. Submillimeter Waves 20 , 497–515 (1970).

Chiang, K. S. Analysis of optical fibers by the effective-index method. Appl. Opt. 25 , 348–354 (1986).

Hocker, G. B. & Burns, W. K. Mode dispersion in diffused channel waveguides by the effective index method. Appl. Opt. 16 , 113–118 (1977).

Van De Velde, K., Thienpont, H. & Van Geen, R. Extending the effective index method for arbitrarily shaped inhomogeneous optical waveguides. J. Light. Technol. 6 , 1153–1159 (1988).

COMSOL Multiphysics v. 5.6 (COMSOL; 2023); www.comsol.com

Nikkhah, V. et al. Replication data for ‘Inverse-designed low-index-contrast structures on silicon photonics platform for vector-matrix multiplication’ (Zenodo, 2023); https://doi.org/10.5281/zenodo.10083901

Download references

Acknowledgements

This work is supported in part by the US Air Force Office of Scientific Research (AFOSR) Multidisciplinary University Research Initiative (MURI) grant no. FA9550-21-1-0312 (to N.E.) and in part by the US Office of Naval Research (ONR) grant no. N00014-19-1-2248 (to F. Aflatouni.).

Author information

Authors and affiliations.

Department of Electrical and Systems Engineering, University of Pennsylvania, Philadelphia, PA, USA

Vahid Nikkhah, Ali Pirmoradi, Farshid Ashtiani, Brian Edwards, Firooz Aflatouni & Nader Engheta

Nokia Bell Labs, Murray Hill, NJ, USA

Farshid Ashtiani

You can also search for this author in PubMed   Google Scholar

Contributions

N.E., F. Aflatouni. and B.E. conceived the idea, envisioned the experiments and supervised the project. V.N. conducted theoretical analysis, numerical simulations and inverse-design of the structures. A.P., F. Ashtiani. and B.E. prepared the designs for nanofabrication by the Advanced Micro Foundry (AMF) and designed the experiments. A.P. performed the experiments and collected data. All authors reviewed, studied and discussed the experimental and numerical simulation results, and discussed the main outcomes of the project. V.N. prepared the first draft of the main text and the Supplementary Information. All authors subsequently worked on the manuscript up to its completion for submission.

Corresponding author

Correspondence to Nader Engheta .

Ethics declarations

Competing interests.

The authors declare no competing interests.

Peer review

Peer review information.

Nature Photonics thanks Yannick Salamin and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

Additional information

Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Supplementary information

Supplementary information.

Supplementary Figs. 1–6, Discussion and Table 1.

Rights and permissions

Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.

Reprints and permissions

About this article

Cite this article.

Nikkhah, V., Pirmoradi, A., Ashtiani, F. et al. Inverse-designed low-index-contrast structures on a silicon photonics platform for vector–matrix multiplication. Nat. Photon. (2024). https://doi.org/10.1038/s41566-024-01394-2

Download citation

Received : 24 February 2023

Accepted : 18 January 2024

Published : 16 February 2024

DOI : https://doi.org/10.1038/s41566-024-01394-2

Share this article

Anyone you share the following link with will be able to read this content:

Sorry, a shareable link is not currently available for this article.

Provided by the Springer Nature SharedIt content-sharing initiative

Quick links

  • Explore articles by subject
  • Guide to authors
  • Editorial policies

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

insert vector 2d

IMAGES

  1. vector insert function

    insert vector 2d

  2. How to Insert a vector image

    insert vector 2d

  3. How to Ligate an Insert into a Vector

    insert vector 2d

  4. Understanding Vector insert() in C++

    insert vector 2d

  5. C++ vector insert

    insert vector 2d

  6. How to Insert a Vector Image

    insert vector 2d

VIDEO

  1. VECTOR 1

  2. VECTOR 1. COLUMN VECTORS IN 2 DIMENSIONS

  3. Directional Vector

  4. Vector 2 animation

  5. Vector 3d Animation

  6. 2D vector animation / After Effects / Design Expert

COMMENTS

  1. c++

    Inserting elements into 2D vector Ask Question Asked 9 years, 2 months ago Modified 3 years, 11 months ago Viewed 54k times 8 so I'm creating a class that implements an adjacency list. Currently in my class definition I initialized two vectors: vector<vector<int>> adjList; vector<int> neighbors;

  2. 2D Vectors in C++

    1 0 1 0 1 1 0 1 The use of 'vector<vector<>>' symbolizes that we are working on a vector of vectors. Each value inside the first set of braces, like ' {1, 0, 1}' and ' {0, 1}' are vectors independently. Note: To create 2D vectors in C++ of different data-type, we can place the data-type inside the innermost angle brackets like <char>.

  3. 2D Vector In C++ With User Defined Size

    A 2D vector is a vector of the vector. Like 2D arrays, we can declare and assign values to a 2D vector! Assuming you are familiar with a normal vector in C++, with the help of an example we demonstrate how a 2D vector differs from a normal vector below: C++ /* C++ program to demonstrate a 2D vector where each of its elements is of different size.

  4. std::vector<T,Allocator>::insert

    constexpr iterator insert( const_iterator pos, std::initializer_list<T> ilist ); (since C++20) Inserts elements at the specified location in the container. 1,2) Inserts value before pos. 3) Inserts count copies of the value before pos. 4) Inserts elements from range [first,last) before pos.

  5. ::insert

    <vector> std:: vector ::insert C++98 C++11 Insert elements The vector is extended by inserting new elements before the element at the specified position, effectively increasing the container size by the number of elements inserted.

  6. Understanding Vector insert() in C++

    Then we call the insert () function on the vector vec with parameters vec.begin () and 10 (new value). Note, here vec.begin () returns an iterator pointing to the start of the vector, After the insertion has been done we print the new vector using a simple for loop to see the resultant vector. 2. Insert the same value Multiple times.

  7. Add elements to your vector using Vector::push_back() in C++

    First way describes how to make a 2D vector and insert row and column wise elements: vector <vector<int>> Myvector; //Declaring a vector of vectors. for (int rowNumber=0; rowNumber <= 10; rowNumber++) { int Value = 1; vector<int>Column; // column vector of the previously declared one.

  8. 2D Vectors in C++: Declaration, Operations & Traversal

    Method 01) Using the above syntax. /* Welcome to favTutor */ #include<vector> using namespace std; int main () { // Normal 2D vector initialization vector < vector <int>> vect; return 0 ; } Method 02) Initializing a 2D vector with vectors as elements inside it.

  9. vector insert() Function in C++ STL

    1. Insert an Element at the Given Index Syntax of insert () in Vector vector_name.insert (position, val); Parameters The function accepts two parameters specified below: position - It specifies the iterator which points to the position where the insertion is to be done. val - It specifies the value to be inserted. Example of insert () in vector C++

  10. c++

    1 Answer Sorted by: 2 I'm not sure if I understand your requirements correctly, but: std::vector<std::vector<int>> grid (4); // 4 rows grid [3].resize (3) // resize 4th row grid [3] [2] = 42; Your 2D grid would then "look" like that:

  11. 2D Vector in C++

    Specifying the Size for 2D Vector Initialization. The 2D vector can be initialized with a user-defined size as well. It is similar to using the new operator or malloc() to create a 2D dynamic array. Consequently, if we want to establish a 2D vector to rows n and columns m, we must start a 2D vector of size n with elements from a 1D vector of size m. We may accomplish that by following the ...

  12. How to Append Vector to Vector in C++

    Use the insert Function to Append Vector to Vector in C++. The insert method is a built-in function of the std::vector container that can add multiple elements to the vector objects. As the first example, we show how to append a given range from one vector to another. If we specify three iterators as arguments, the insert function will add ...

  13. numpy.insert

    numpy.insert # numpy.insert(arr, obj, values, axis=None) [source] # Insert values along the given axis before the given indices. Parameters: arrarray_like Input array. objint, slice or sequence of ints Object that defines the index or indices before which values is inserted. New in version 1.8.0.

  14. Insert Element at Specific index in Vector in C++

    Inserting a single element at specific position in vector. We are going to use first overloaded version of Vector's insert () function i.e. Copy to clipboard. iterator insert (const_iterator pos, const value_type& val); It Inserts a copy of give element "val", before the iterator position " pos " and also returns the iterator pointing ...

  15. Mastering 2D Vector Operations in C++: Tips and Tricks

    Also Read: Best Practices to Insert Vector in C++: A Guide to 'insert ... What are some real-world applications of 2D vector operations in C++? 2D vector operations find applications in computer graphics, video games, simulations, physics engines, robotics, and various engineering fields. They are crucial in solving problems related to motion ...

  16. c++

    How to implement 2D vector array? Ask Question Asked 11 years, 11 months ago Modified 3 years, 5 months ago Viewed 267k times 37 I'm using the vector class in the STL library for the first time. How should I add to a specific row of the vector array? struct x { vector <vector <int> > v; int row; }; vector< int* > my ints; int add;

  17. Vector of Vectors in C++ STL with Examples

    Insertion in Vector of Vectors Elements can be inserted into a vector using the push_back () function of C++ STL. Below example demonstrates the insertion operation in a vector of vectors. The code creates a 2D vector by using the push_back () function and then displays the matrix. Syntax:

  18. Best Practices to Insert Vector in C++: A Guide to 'insert'

    In this example, the 'insert' function is used to add the elements from 'additional_numbers' into the 'numbers' vector. Also Read: Mastering Function Pointers in C++: A Comprehensive Guide By specifying the iterators representing the range, all the elements are inserted in one operation.

  19. 2D Vector of Pairs in C++ with Examples

    insert (): It inserts new elements before the element at the specified position. Complexity-O (1). What is 2D vector? In C++, a 2D vector is a vector of vectors which means that each element of a 2D vector is a vector itself. It is the same as a matrix implemented with the help of vectors. Some of the functions associated with a 2D vector:

  20. Inserting 1D vector into 2D vector Without Creating Temp 1D Vector

    2,727 8 47 78 Add a comment 4 Answers Sorted by: 2 There are 2 ways. The first way is to make table a vector of pointers to vector instead of a vector of vectors. ie: vector<vector<string>*> table

  21. Inverse-designed low-index-contrast structures on a silicon photonics

    We designed and experimentally demonstrated a vector-matrix product for a 2 × 2 matrix and a 3 × 3 matrix. We also designed a 10 × 10 matrix using the proposed 2D computational method.

  22. Input element by user into 2D vector c++

    11 Answers Sorted by: 9 Here is the solution std::vector<vector<int>> d; //std::vector<int> d; cout<<"Enter the N number of ship and port:"<<endl; cin>>in; cout<<"\Enter preference etc..:\n"; for (i=0; i<in; i++) { cout<<"ship"<<i+1<<":"<<' '; for (j=0; j<in; j++) { cin>>temp; d [i].push_back (temp); } } Share Improve this answer Follow