std::bind示例一

代码

class A {
public:
    void fun(int a, int b, int c) {
        std::cout << "A::fun()" << std::endl;
        std::cout << a << std::endl;
        std::cout << b << std::endl;
        std::cout << c << std::endl;
    }
};

int main() {
    A a;
    using namespace std::placeholders;
    std::function<void(int)> f1 = std::bind(&A::fun, a, _ 1, 99, 99);
    std::function<void(int)> f2 = std::bind(&A::fun, a, 99, _ 1, 99);
    std::function<void(int)> f3 = std::bind(&A::fun, a, 99, 99, _ 1);
    std::function<void(int, int)> f4 = std::bind(&A::fun, a, 99, _ 1, _ 2);

    f1(1);
    f2(1);
    f3(1);
    f4(1, 2);
    return system("pause");
}

输出结果

A::fun()
1
99
99
A::fun()
99
1
99
A::fun()
99
99
1
A::fun()
99
1
2

std::bind示例二

#include <iostream>
#include <functional>

// a function: (also works with function object: std::divides<double> my_divide;)
double my_divide(double x, double y) { return x / y; }

struct MyPair {
    double a, b;
    double multiply() { return a * b; }
};

int main() {
    using namespace std::placeholders;    // adds visibility of _ 1, _ 2, _ 3,...

    // binding functions:
    auto fn_five = std::bind(my_divide, 10, 2);              // returns 10/2
    std::cout << fn_five() << '\n';                          // 5

    auto fn_half = std::bind(my_divide, _ 1, 2);              // returns x/2
    std::cout << fn_half(10) << '\n';                        // 5

    auto fn_invert = std::bind(my_divide, _ 2, _ 1);           // returns y/x
    std::cout << fn_invert(10, 2) << '\n';                   // 0.2

    auto fn_rounding = std::bind<int>(my_divide, _ 1, _ 2);    // returns int(x/y)
    std::cout << fn_rounding(10, 3) << '\n';                 // 3

    MyPair ten_two{10, 2};

    // binding members:
    auto bound_member_fn = std::bind(&MyPair::multiply, _ 1); // returns x.multiply()
    std::cout << bound_member_fn(ten_two) << '\n';           // 20

    auto bound_member_data = std::bind(&MyPair::a, ten_two); // returns ten_two.a
    std::cout << bound_member_data() << '\n';                // 10

    return 0;
}