How to Check if a std::mutex is Locked in C

In C the std::mutex class is used for synchronization between multiple threads. It ensures that only one thread can access a critical section of code at a time, preventing race conditions and data inconsistencies.

Sometimes, it becomes necessary to check whether a std::mutex is currently locked or not. Here's a simple way to do that:

1. Pass a std::unique_lock as an argument to the function:

```cpp
#include
#include
#include

std::mutex mtx;

void locked(std::unique_lock& lck) {
// Critical section of code here
std::this_thread::sleep_for(std::chrono::milliseconds(1000));
}

bool is_locked(std::mutex& mtx) {
std::unique_lock lck(mtx);
return lck.owns_lock();
}
```

In this example, we have a mutex `mtx` and a function `locked` that represents a critical section of code.

We've also created a helper function `is_locked` how to check if std mutex is locked checks if the mutex is currently locked.

2. Use the `is_locked` function:

```cpp
int main() {
std::thread t1(locked, std::ref(mtx));
std::thread t2(is_locked, std::ref(mtx), std::ref(mtx.try_lock()));

t1.join();

how to check if std mutex is locked if (t2.get_id() != std::this_thread::get_id()) {
if (std::get<0>(t2.get_future()).get<0>()) {
std::cout << "The mutex is locked.\n";
} else {
std::cout << "The mutex is not locked.\n";
}
}

t2.join();
return 0;
}
```

In the `main` function, we create two threads: one that calls the `locked` function and another that calls the `is_locked` function.

The second thread also attempts to lock the mutex using `mtx.try_lock()`. If the mutex is already locked by another thread, `try_lock` will return false, and the second thread can still check if the mutex is locked or not.

At the end of the `main` function, we wait for both threads to complete their tasks and then check the result of the `is_locked` call to determine if the mutex was locked during the execution.