std::mutex::unlock

 

C++

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Thread support library

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thread (C++11)
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mutex (C++11) timed_mutex (C++11)	recursive_mutex (C++11) recursive_timed_mutex (C++11)
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lock_guard (C++11) unique_lock (C++11) defer_lock_t try_to_lock_t adopt_lock_t (C++11) (C++11) (C++11)	lock (C++11) try_lock (C++11) defer_lock try_to_lock adopt_lock (C++11) (C++11) (C++11)
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std::mutex

Member functions

mutex::mutex

Locking

mutex::lock

mutex::try_lock

mutex::unlock

Native handle

mutex::native_handle

 

void unlock();		(since C++11)

Unlocks the mutex.

The mutex must be unlocked by all threads that have successfully locked it before being destroyed. Otherwise, the behavior is undefined.

Parameters

(none)

Return value

(none)

Exceptions

(none)

Example

This example shows lock, try_lock and unlock in action

run this code

#include <iostream>
#include <mutex>
 
int main()
{
    std::mutex test;
    if (test.try_lock()==true)
        std::cout << "lock acquired" << std::endl;
    else
        std::cout << "lock not acquired" << std::endl;
    test.unlock();	//now unlock the mutex
    test.lock();	//to lock it again
    if (test.try_lock())  //true can be left out
        std::cout << "lock acquired" << std::endl;
    else
        std::cout << "lock not acquired" << std::endl;
    test.lock(); //and now the finale (a block)
}

Output:

lock acquired
lock not acquired
(program hangs)

See also

lock	locks the mutex, blocks if the mutex is not available (public member function)
try_lock	tries to lock the mutex, returns if the mutex is not available (public member function)