一些函数指针总结（General STL BOOST）

1、关于C函数指针，C++静态函数指针，非静态函数指针，std::mem_fun, 以及boost::function的小结：

/*关于C函数指针，C++静态函数指针，非静态函数指针，std::mem_fun, 以及boost::function的小结。 Section I ================ general function pointer usagefunction pointer can point to1. general c-style function2. template c-style function3. general c++ static member function, which is totally the same with c-style function4. c++ static member function which was used to delegate general non-static member function. the benefit of this usage is, we can use function pointer to base class to delegate member function of derived class.all usage can be found in the following example. run it and get a feeling.*/#include <boost/lambda/lambda.hpp>#include <iostream>#include <iterator>#include <algorithm>using namespace std;class Base;class A;//c or c++ static member functionint (*function_pointer_c_style)(int,int);//c++ non-static member functionint (A::*function_pointer_class_non_static_style)(int,int);//c++, use static-style member function to delegate non-static member functionint (*function_pointer_class_static_delegate_style)(void*, int,int);int sum(int a, int b){ cout << "call non-template c-style function" << endl; cout << a << " + " << b << " = " << a + b << endl; cout << endl;}template <class A, class B>int sum(A a, B b){ cout << "call template c-style function" << endl; cout << a << " + " << b << " = " << a + b << endl; cout << endl;}template <class T>int multi(T a, int b){ cout << "function pointer which point to template function" << endl; cout << a << " * " << b << " = " << a * b << endl; cout << endl;}class Base{public: int SumNonStatic( int a, int b) { cout << "call base class non-static member function" << endl; cout << "Base class: " << a << " + " << b << " = " << a + b << endl; cout << endl; }};class A : public Base{public: static int Sum(int a, int b) { cout << "call class static member function" << endl; cout << a << " + " << b << " = " << a + b << endl; cout << endl; } int SumNonStatic( int a, int b) { cout << "call class non-static member function" << endl; cout << "Derived class: " << a << " + " << b << " = " << a + b << endl; cout << endl; } static int Delegate(void*p, int a, int b) { //base to derived, use static_cast but dynamic_cast A* pa = static_cast<A*>(p); cout << "use static member function to delegate non-static member function. " << endl; pa->SumNonStatic(a, b); cout << endl; }};int main(){ function_pointer_c_style = sum; //the full format should be (*funtion_pointer)(para1, para2... ) //the short format function_pointer(para1, para2...) is also right in C //but in c++, we must use (object.*function_pointer)(para1, para2...) (*function_pointer_c_style)(3,4); function_pointer_c_style = multi<int>; function_pointer_c_style(3,4); function_pointer_c_style = &A::Sum; function_pointer_c_style(3,4); function_pointer_class_non_static_style = &A::SumNonStatic; A a; (a.*function_pointer_class_non_static_style)(3,4); function_pointer_class_static_delegate_style = &A::Delegate; function_pointer_class_static_delegate_style((void*)(&a), 3, 4); return 0;}/*@see http://www.newty.de/fpt/intro.html for detailed instruction Section II ================ std::mem_fun etc...in following section, we will show the std::mem_fun and some related concept, such as bind1st and bind2st ..the mechanisms of mem_fun is similar to http://www.newty.de/fpt/functor.html. std::mem_fun or std::mem_fun_ref1. only support non-parameter or one-parameter function, also bind1st, bind2nd ...2. if we want to support arbitrary parameter, we can use http://www.newty.de/fpt/functor.html. to to customerize "mem_fun" of our-selves. but i recommend boost::function and boost::bind, which is very easy to use. see Section III*/#include <iostream>#include <functional>using namespace std;class A{public: int NonPara() { cout << "member function without parameter!" << endl; cout << endl; return 0; } int OnePara(int para) { cout << "member function with one parameter:" << para << endl; cout << endl; return 0; } int TwoPara(int a, int b) { cout << "member function with two parameter:" << endl; cout << a << " + " << b << " = " << a + b << endl; cout << endl; return 0; } int MultiPara(int a, int b, int c) { cout << "member function with multi parameter:" << endl; cout << a << " + " << b << " + " << c << " = " << a + b + c << endl; cout << endl; return 0; }};int main(){ mem_fun_t<int, A> std_mem_fun_non_para = mem_fun<int, A>(&A::NonPara); //mem_fun_ref is similar to mem_fun, except that //mem_fun_ref require reference to object as its first parameter mem_fun_ref_t<int, A> std_mem_fun_non_para_ref = mem_fun_ref<int, A>(&A::NonPara); mem_fun1_t<int, A, int> std_mem_fun_one_para = mem_fun<int, A>(&A::OnePara); A a; std_mem_fun_non_para(&a); std_mem_fun_non_para_ref(a); std_mem_fun_one_para(&a, 3); //show bind1st. //next time we needn't pass object as first parameter, just pass the real para //such as call member function directly std::binder1st<std::mem_fun1_t<int, A, int> > std_mem_fun_non_para_with_object_bound = bind1st(std_mem_fun_one_para, &a); cout << "use bind1sh to bind object pointer" << endl; std_mem_fun_non_para_with_object_bound(2); cout << endl; return 0;}/* Section III ================ boost::function and boost::bind the above difficulty can be easily solved by boost::function. boost::function is extended mem_fun, and boost::bind is extended bind1st ...see follow links://http://www.boost.org/doc/libs/1_40_0/libs/bind/bind.html#with_functions//http://www.boost.org/doc/libs/1_35_0/doc/html/function/tutorial.html*/#include <boost/function.hpp>#include <boost/bind.hpp>#include <iostream>#include <functional>using namespace std;class A{public: int NonPara() { cout << "member function without parameter!" << endl; cout << endl; return 0; } int OnePara(int para) { cout << "member function with one parameter:" << para << endl; cout << endl; return 0; } int TwoPara(int a, int b) { cout << "member function with two parameter:" << endl; cout << a << " + " << b << " = " << a + b << endl; cout << endl; return 0; } int MultiPara(int a, int b, int c) { cout << "member function with multi parameter:" << endl; cout << a << " + " << b << " + " << c << " = " << a + b + c << endl; cout << endl; return 0; }};int main(){ //we don't use typedef for easy read. typedef should be used in practice A a; //use boost::function only, Note: A* must be a first parameter boost::function<int (A*, int, int, int)> member_function_with_boost_function_only = &A::MultiPara; member_function_with_boost_function_only(&a, 3, 4, 5 ); // object as first parameter when call it //use boost::function and boost::bind. Note: returned function object have no A* as first para boost::function<int (int, int, int)> member_function_with_boost = boost::bind(&A::MultiPara, &a, _1, _2, _3); member_function_with_boost(3,4,5);//call directly, similar to member function return 0;}

 

 

 

2、How to use STL helper template function mem_fun in sophisticated algorithms

     http://www.codeproject.com/KB/stl/xingstlarticle.aspx?display=Mobile

 

 

3、引领boost（六）（boost::bind）

   http://www.cppblog.com/mzty/archive/2007/09/05/31622.html