std::function 和 std::bind 的简单例子

#include <QCoreApplication>
#include <functional>
#include <iostream>
using namespace std;

void print()
{
    std::cout << "here is print" <<'\n';
}

void print_num(int i)
{
    std::cout << i << '\n';
}

void print_add(int i, int j)
{
    std::cout << i+j << '\n';
}

class Foo
{
public:
    Foo(int data)
    {
        m_data = data;
    }

    void print_sum(int n1, int n2)
    {
        std::cout << n1 + n2 << std::endl;
    }
    int m_data;
};

int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);
    using namespace std::placeholders;
//-------------------------------------------------------
    //调用void print()函数
    //1.不使用std::bind
    std::function<void()> f = print;
    f();
    //2.使用std::bind
    std::function<void()> f_bind = std::bind(print);
    f_bind();

    //调用void print_num(int i)函数
    //1.不使用std::bind
    std::function<void(int)> ff = print_num;
    ff(12345);
    //2.使用std::bind
    std::function<void()> ff_bind = std::bind(print_num, 12345);
    ff_bind();

    //调用void print_adds(int i, int j)函数
    //1.不使用std::bind
    std::function<void(int,int)> fff = print_add;
    fff(1,2);
    //2.使用std::bin
    std::function<void()> fff_bind = std::bind(print_add, 1,2);
    fff_bind();
//-------------------------------------------------------
    // 绑定指向成员函数指针
    //使用auto自动推导数据类型
    Foo *foo = new Foo(20);
    std::function<void()> f1 = std::bind(&Foo::print_sum, foo, 95, 4);
    f1();
    std::function<void(int)> f2 = std::bind(&Foo::print_sum, foo, 95, _1);
    f2(5);
    auto f3 = std::bind(&Foo::print_sum, foo, 95, 6);
    f3();
    auto f4 = std::bind(&Foo::print_sum, foo, 95, _1);
    f4(7);
    return a.exec();
}