How to use push_back() and pop_back() vector functions in C++

The push_back() function

The push_back() function is used to insert an element at the end of a vector. This function is available in the <vector> header file.

Parameters

The push_back() function accepts one parameter, val, which specifies the value inserted at the end of the vector.

Return value

The push_back() function does not return anything.

Code

Now, let’s see the code and see how the push_back() function is used:

#include <iostream>
#include <vector>
using namespace std;
int main() {
  vector<int> vec = {1,2,3};
  cout << "Original Vector: ";
  for(int x: vec)
    cout << x << " ";
  
  vec.push_back(5);
  vec.push_back(10);
  cout << "\nVector after pushing some values: ";
  for(int x: vec)
    cout << x << " ";
  return 0;
}

Explanation

  • In lines 1 and 2, we import the required packages.
  • In lines 6 and 9, we create a vector that contains integers, and print the elements.
  • In lines 11 and 12, we call the push_back() function and insert some integer values.
  • In lines 13 and 15, we create and print the elements of the vector. We can see that the elements have been added at the end of the vector.

The pop_back() function

The pop_back() function is used to remove the last element from the vector. This function is available in the <vector> header file.

Parameters

The pop_back() function does not accept any parameters.

Return value

The pop_back() function does not return anything.

Code

Now, let’s look at the code and see how to use the pop_back() function:

#include <iostream>
#include <vector>
using namespace std;
int main() {
  vector<int> vec = {1,2,3,4,5,6,7};
  cout << "Original Vector: ";
  for(int x: vec)
    cout << x << " ";
  
  vec.pop_back();
  vec.pop_back();
  cout << "\nVector after popping some values: ";
  for(int x: vec)
    cout << x << " ";
  return 0;
}

Explanation

  • In lines 1 and 2, we import the required packages.
  • In lines 6 and 9, we create a vector that contains integers and print the elements.
  • In lines 11 and 12, we call the pop_back() function and insert some integer values.
  • In lines 13 and 15, we create and print the elements of the vector. We can see that two elements have been removed from the last of the vector.
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