Function adapter for member functions

In addition to providing regular function adapters, the STL standard library also provides two function adapters for member functions. Their main function is to use these adapters, you can directly call its member functions for each element.

There are two such member function adapters:

Mem_fun_ref (OP) calls the object's member function op

Mem_fun (OP) calls the object pointer member function op

Both function receivers call the member function op in the object. For these two member functions, the const member function of the object can only be called in the past, but the current situation seems to have changed, all member functions can be called.

An example is as follows:

# Include <iostream> # include <functional> # include <deque> # include <algorithm> # include <iterator> using namespace STD; Class A {public: A (int B ): A (B ){}~ A () {} void mfun () {ostream_iterator <int> (cout, "--") = ++ A;} PRIVATE: int A ;}; int main () {deque <A> de; For (INT I = 0; I <5; I ++) de. push_back (A (I); for_each (de. begin (), de. end (), mem_fun_ref (& A: mfun); cout <Endl; deque <A *> de2; For (INT I = 0; I <5; I ++) de2.push _ back (new A (I); for_each (de2.begin (), de2.end (), mem_fun (& A: mfun )); /* 1--2--3--4--5--1--2--3--4--5 -- press any key to continue... */}

Note:

1. The member functions called through this type of adapter must exist in the object type.

2. The parameters of the two receivers must be the offset of the member functions in the type passed, and the function name cannot be directly transferred.