回调中的std :: bind和std :: function用法

#include<iostream>
#include<functional>

void print(int a, int b) {
    std::cout << a << " + " << b << " = " << a + b<< std::endl;
}

int main() {
    auto bound_print = std::bind(print, 10, std::placeholders::_1);
    bound_print(20); // 输出 "10 + 20 = 30"
    return 0;
}

#include<iostream>
#include<functional>

int add(int a, int b) {
    return a + b;
}

int main() {
    std::function<int(int, int)> func = add;
    std::cout<< func(10, 20)<< std::endl; // 输出 "30"
    return 0;
}