C++11 占位符placeholders和函数bind用法

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#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; }<br><br><br>参照 https://blog.csdn.net/aa838260772/article/details/39828207