How do I know what is the sys error in pthread_mutex_destroy?

I'm using the command 'pthread_mutex_destroy(&lock);'.

When I check the return value - it returns the number 16.

In the man page of this command it is said that a non-zero value is returned on failure, but there is 开发者_如何学JAVAno specified way to check it.

How can I know what is the source of my error if I have no access to errno messages?

Commandline: perror 16

Source: perror("pthread_mutex_destroy");

Or use strerror(16);