C++11的function bind回调机制

#include <functional>

using namespace std::placeholders;

1.可以提前声明函数类型:function< 返回值 ( 参数列表) >  函数名;

function< int (int, double, string) > fn

也可以不用声明类型直接bind前面：auto fn = bind(  ....)

函数参数的对应：

以实际函数的参数对应声明的位置：

int test(double, string, int)

fn = bind(test, _2, _3, _1)  -->test参数的第一个类型double，对应于function的_2位置，

也可设置常量参数，fn = bind(test, 3.5, "hello", 6);

2.bind类的成员函数时：

bind(&A::print, &a, ...)

#include <iostream>
#include <string>
#include <functional>
using namespace std;
using namespace std::placeholders;

void test(int i, double d, const string &s)
{
    cout << "i= " << i << " d= " << d <<" s= " << s << endl;
}
int test1(int i, double d, const string &s)
{
    cout << "i= " << i << " d= " << d <<" s= " << s << endl;
    return i;
}

int main(int argc, const char *argv[])
{
    function<void( void )> fp;
    string s = "foo";
    int a = 3;
    double b = 6.7;
    fp = bind(&test, a, b, s);
    fp();

    function <void (int , const string&)> fp1;
    double b2 = 4.6;
    fp1 = bind(test, _1, b2, _2);
    fp1(4, "kity");

    function <int (int , const string&) > fp2;
    fp2 = bind<int>(test1, _1, b2, _2);
    int  y = fp2(4, "kity");
    cout << y << endl;

    auto fn = bind(test, 10, 23.3, "heko");//不用function指定函数参数，
    fn();

    auto ff = bind(test, _1, _3, _2);//bind中的i参数类型与test的_j的参数类型对应
    ff(12, "ppp", 12.5);

    class A
    {
        public:
            void print(int a, double x)
            {
                cout << a << " " << x << endl;
            }
    };
    A a3;
    auto fclass= bind(&A::print, &a3, 11, 7.7);
    fclass();
    return 0;
}