How does std::for_each work in multithreading with C++?

Can you explain how std::for_each works in a multithreading context in C++?

Sure! std::for_each can be used with multithreading to apply a function to a range of elements concurrently. You can use it with execution policies like std::execution::par to enable parallel execution.

What are execution policies, and how do they affect performance?

Execution policies define how algorithms execute. For example, std::execution::par allows parallel execution, which can significantly improve performance on large datasets by utilizing multiple threads.

Can you give me a code example of std::for_each with multithreading?

Certainly! Here's a simple example:

#include <vector>
#include <algorithm>
#include <execution>

int main() {
    std::vector<int> vec = {1, 2, 3, 4, 5};
    std::for_each(std::execution::par, vec.begin(), vec.end(), [](int &n) { n *= 2; });
}

This code doubles each element in the vector using parallel execution.

Are there any limitations or considerations when using std::for_each with multithreading?

Yes, you should ensure that the function you pass to std::for_each is thread-safe. Also, be cautious of data races if you're modifying shared data.