U cannot pass a non static member function to pthread_create as non static member function includes an implicit "this" pointer.
U can consider following two solutions depending on your requirements.
1. Declare funDequeue() as static function.(No this pointer in case of static functions)
2. Write a helper function(non member ) which takes object of class cDequeue as parameter and then calls function funDequeue().
void * helper(void * Obj)
cDequeue * ptr = (cDequeue *) Obj;
ptr -> funDequeue();