#include <pthread.h> int pthread_rwlockattr_init(pthread_rwlockattr_t *attr);
pthread_rwlockattr_init(3T) initializes a read-write lock attributes object attr with the default value for all of the attributes defined by the implementation.
Results are undefined if pthread_rwlockattr_init is called specifying an already initialized read-write lock attributes object. After a read-write lock attributes object has been used to initialize one or more read-write locks, any function affecting the attributes object (including destruction) does not affect any previously initialized read-write locks.
If successful, pthread_rwlockattr_init() returns zero. Otherwise, an error number is returned to indicate the error.