Remove empty elements from a vector of strings in C++

This post will discuss how to remove empty elements from a vector of strings in C++.

1. Using Erase-remove idiom

The recommended way to remove empty elements from a vector is using the Erase-remove idiom. Since the std::remove_if algorithm does not know the underlying container, it cannot remove elements from it. Only a call to the vector::erase algorithm actually removes elements.

A typical implementation of this approach would look like below:

#include <iostream>

#include <string>

#include <vector>

#include <algorithm>

int main()

{

std::vector<std::string> v = { "A", "", "B", " ", "C", "\t", "D" };

auto isEmptyOrBlank = [](const std::string &s) {

return s.find_first_not_of(" \t") == std::string::npos;

};

v.erase(std::remove_if(v.begin(), v.end(), isEmptyOrBlank), v.end());

for (const auto &s : v ) {

std::cout << s << ' ';

}

return 0;

}

Download Run Code

Output:

A B C D

2. Using `std::erase_if`

Since C++20, we can use the std::erase_if algorithm to remove all elements from the vector satisfying a predicate. It is defined in header <vector> and acts as a wrapper over the Erase-remove idiom.

The following code example shows invocation for this method: