Vector push_back() in C++ STL

In C++, the vector push_back() is a built-in method used to add a new element at the end of the vector. It automatically resizes the vector if there is not enough space to accommodate the new element.

Let’s take a look at an example that illustrates the vector push_back() method:

#include <bits/stdc++.h>
using namespace std;

int main() {
    vector<int> v = {1, 4, 6};

    // Add an element at the end of the vector
    v.push_back(9);

    for (int i : v)
        cout << i << " ";
    return 0;
}

1 4 6 9 

This article covers the syntax, usage, and common examples of the vector push_back() method in C++:

Syntax of Vector push_back()

The vector push_back() is a member method of the std::vector class defined inside the <vector> header file.

v.push_back(val);

Parameters:

• val: Element to be added to the vector at the end.

Return Value:

• This function does not return any value.

Examples of vector push_back()

The following examples demonstrate the use of the vector push_back() function for different purposes:

Initialize an Empty Vector One by One

#include <bits/stdc++.h>
using namespace std;

int main() {
    vector<int> v;

    // Add elements to the vector
    v.push_back(3);
    v.push_back(7);
    v.push_back(9);

    for (int i : v)
        cout << i << " ";
    return 0;
}

3 7 9 

Add Elements Vector of Strings at the End

#include <bits/stdc++.h>
using namespace std;

int main() {
    vector<string> v = {"Hello", "Geeks"};

    // Add string to the vector
    v.push_back("Welcome");

    for (string s: v) 
        cout << s << " ";
    return 0;
}

Hello Geeks Welcome