C++11的function bind回调机制

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#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;}

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