1 使用特点

加 :: 变量使用

#include <iostream>
using namespace std;
int qwer = 100;
int asdf = 900;
void sitl(){std::cout <<"globe dog is sitting." << std::endl;
}class Cat {
public:static int num;};
int Cat::num = 99;class Dog {
private:string name; // 成员变量，存储狗的名字public:// 成员函数，让狗叫void bark(){cout <<"dog says woof!" << std::endl;}// 成员函数，让狗坐下void sit(){cout <<"dog is sitting." << std::endl;}
};
int main()
{int qwer = 200;cout << "Hello, world!   " << ::qwer <<endl;cout << "Hello, c++  !   " << ::asdf <<endl;cout << "Hello, cat  !   " << ::Cat::num <<endl;Dog Doga;Doga.sit();::sitl();return 0;
}