What are mutexes in C++ and how do they work?

What are mutexes in C++ and how do they work?

Mutexes, or mutual exclusions, are synchronization primitives used in C++ to prevent multiple threads from accessing shared resources simultaneously.

Can you explain how to implement a mutex in a C++ program?

Sure! You can use the std::mutex class from the <mutex> header. Here's a simple example:

#include <iostream>
#include <thread>
#include <mutex>

std::mutex mtx;

void printThreadId(int id) {
    mtx.lock();  // Lock the mutex
    std::cout << "Thread ID: " << id << '\n';
    mtx.unlock();  // Unlock the mutex
}

int main() {
    std::thread threads[5];
    for (int i = 0; i < 5; ++i) {
        threads[i] = std::thread(printThreadId, i);
    }
    for (auto& th : threads) {
        th.join();
    }
    return 0;
}

What happens if I forget to unlock a mutex?

If you forget to unlock a mutex, it can lead to a deadlock situation where other threads are unable to acquire the lock and thus cannot proceed, potentially freezing your program.

Are there alternatives to mutexes for thread synchronization?

Yes, alternatives include condition variables, semaphores, and read-write locks, each with its own use cases and advantages.