What is std::copy_if in C++?

Can you explain what std::copy_if does in C++?

Sure! std::copy_if is a function that copies elements from one range to another based on a specified condition.

How do I use std::copy_if in my code?

You can use it by including the <algorithm> header and providing a source range, a destination iterator, and a predicate.

Can you give me a code example?

Of course! Here's a simple example:

#include <algorithm>
#include <vector>
#include <iostream>

int main() {
    std::vector<int> numbers = {1, 2, 3, 4, 5};
    std::vector<int> evenNumbers;

    std::copy_if(numbers.begin(), numbers.end(), std::back_inserter(evenNumbers), [](int n) { return n % 2 == 0; });

    for (int n : evenNumbers) {
        std::cout << n << ' ';
    }
}

This will copy all even numbers from the 'numbers' vector to 'evenNumbers'.

What happens if the destination range is not large enough?

If the destination range is not large enough to hold the copied elements, it will lead to undefined behavior. Always ensure the destination has enough space.