C++在类的内部声明函数，在类的外部定义函数

//在类的外部定义内部函数
#include
#include
#include
using namespace std;
struct user {
	string id(string id="") {
		if (id.size()) {
			this->user_id = id;
		}
		return this->user_id;
	}
	string user_id;
	string password(string password="") {
		if (password.size()) {
			this->user_password = password;
		}
		return this->user_password;
	}
	string user_password;
	int out();
};
int user::out(){
	cout << "这是一个在类内部声明在类外部定义的函数\n";
	return 0;
};
int main(void) {
	struct user user;
	user.user_id = "gaowanlu";
	user.user_password = "133466377";
	user.password("1234567890");//修改密码
	cout << user.id() << endl;
	cout << user.password() << endl;
	user.out();
	return 0;
}