12345678910111213141516class Foo{public: void operator() () { cout <<"Foo operator"<<endl; } int operator() (int val) { return val*10; }};Foo f;f(); // Foo operatorcout<< f(5) <<endl; // 50 Foo是定义了调用操作符()的类,它的对象就相当于函数名,因此operator()取名叫函数对象