Example of boost: bind in four application scenarios

[Cpp] int f (int a, int B) {return a + B;} int g (int a, int B, int c) {return a + B + c ;} // function pointer defines typedef int (* f_type) (int, int); typedef int (* g_type) (int, int, int); // struct is only used for convenience, do not write public struct demo {int f (int a, int B) {return a + B ;}}; // function object struct sf {int operator () (int, int B) {return a + B ;}}; void test_bind_common () {std: cout <boost: bind (f, 1, 2) () <std:: Endl; std: cout <boost: bind (g, 1, 2, 3) () <std: endl;} // 1. boost: bind void test_bind_fun1 () {// bind (f, _ 1, 9) (x); // f (x, 9 ), equivalent to bind2nd (f, 9) // bind (f, _ 1, _ 2) (x, y); // f (x, y) // bind (f, _ 2, _ 1) (x, y); // f (y, x) // bind (f, _ 1, _ 1) (x, y ); // f (x, x), y parameter ignored // bind (g, _ 1, 8, _ 2) (x, y); // g (x, 8, y) // bind (g, _ 3, _ 2, _ 2) (x, y, z); // g (z, y, y ), the x parameter is ignored. int x = 1, y = 2, z = 3; std: cout <boost: bind (f, _ 1, 9) (x) <std: endl; std: cout <boost :: bind (f, _ 1, _ 2) (x, y) <std: endl; std: cout <boost: bind (f, _ 2, _ 1) (x, y) <std: endl; std: cout <boost: bind (f, _ 1, _ 1) (x, y) <std: endl; std: cout <boost: bind (g, _ 1, 8, _ 2) (x, y) <std: endl; std: cout <boost: bind (g, _ 3, _ 2, _ 2) (x, y, z) <std: endl ;} // 2. member function application boost: bind void test_bind_fun2 () {demo A, & ra = a; demo * p = & a; // The get address operator must be added before the member function &, it indicates that this is a member function pointer // The second parameter uses struct demo. struct demo * Can Be std: cout for both types <boost: bind (& demo: f, a, _ 1, 20) (10) <std: endl; std: cout <boost: bind (& demo: f, ra, _ 2, _ 1) (10, 20) <std: endl; std: cout <boost: bind (& demo: f, p, _ 1, _ 2) (10, 20) <std: endl;} // 3. member Variable void test_bind_val () {typedef std: pair <int, std: string> pair_t; pair_t p (123, "String"); std: cout <boost: bind (& pair_t: first, p) () <std: endl; std :: cout <boost: bind (& pair_t: second, p) () <std: endl ;}// 4. function object void test_bind_functor () {std: cout <boost: bind (std: plus <int> (), _ 1, _ 2) (10, 20) <std: endl; std: cout <boost: bind (std: modulus <int> (), _ 1, 3) (11) <std:: endl; std: cout <std: boolalpha <boost: bind (std: greater <int> (), _ 1, 10) (20) <std :: Endl; std: cout <boost: bind <int> (sf (), _ 1, _ 2) (11, 22) <std: endl ;} // you can use the ref library to wrap the object reference, so that the bind can store the copy of the object reference, thus reducing the copy cost. Void test_bind_ref () {// variable int x = 10; // 11 + 10 + 10 std: cout <boost: bind (g, _ 1, boost :: cref (x), boost: ref (x) (11) <std: endl; // a function object sf af; std: cout <boost :: bind <int> (boost: ref (af), _ 1, _ 2) (11, 22) <std: endl ;}