如下程序声明了一个电话号码类PhoneNumber，重载了流插入运算符＜＜，以便于电话号码的输出。请将程序补充完整。 # include＜iostream＞ # include＜iomanip＞ # include＜string＞ using namespace std; class PhoneNumber{ public: void setNumber(string number) {this--＞number = number;} //重载流插入操作符 friend 【 】 (ostream &output,const PhoneNumber &num) { output＜＜num. number; return output; } private: string number; }; int main() { PhoneNumber phone; phone. setNumber("8008100598"); cout＜＜"The phone number is:"＜＜phone＜＜endl; return 0; }
