Remove all occurrences of an element from a vector in C++

This post will discuss how to remove all occurrences of an element from a vector in C++.

1. Using Erase-remove idiom

The standard solution to remove values from a range is using the std::remove algorithm. However, std::remove doesn’t have any information of the underlying container and hence does not actually remove elements from the container. It expects a call to the std::erase algorithm. This technique knows as the Erase-remove idiom.

#include <iostream>

#include <vector>

#include <algorithm>

#include <iterator>

template<typename T>

void remove(std::vector<T> &v, const T &target)

{

v.erase(std::remove(v.begin(), v.end(), target), v.end());

}

int main()

{

std::vector<int> v = {1, 2, 3, 2, 5, 2, 6, 7};

int target = 2;

// remove all occurrences of target

remove(v, target);

// print the vector

std::copy(v.begin(), v.end(), std::ostream_iterator<int>(std::cout, " "));

return 0;

}

Download Run Code

Output:

1 3 5 6 7

2. Using `std::vector::erase`

Another option is to iterate over the vector and remove all the occurrences of the target from the vector using std::vector::erase function.