C++入门2

1，第一个 C++ 程序

• 编译方式：g++ main.cpp

1.1 输出

• main.cpp

#include <iostream>
using namespace std;

// 输出
int main()
{
    cout << "Hello, World! I am " << 18 << " Today!" << endl;
    return 0;
}

1.2 输入

• main.cpp

#include <iostream>
using namespace std;

// 输入
int main()
{
    int number;
    
    cout << "Enter a decimal number:";
    cin >> number;
    cout << "The number you entered is " << number << endl;
    
    return 0;
}

2，面向对象

• Objects = Attributes + Services
  • Data: the properties or status
  • Operations: the functions

2.1 Procedural Languages(过程语言)

• C doesn't support relationship between data and functions.

// 定义 struct
typedef struct point3d {
        float x;
        float y;
        float z;
    } Point3d;

// 定义 function
void Point3d_print(const Point3d* pd);

Point3d a;
a.x = 1; a.y = 2; a.z = 3;
Point3d_print(&a);

2.2 C++ 版本

// 类里面既包括数据，又包括 function
class Point3d {
    public:
        Point3d(float x, float y, float z);
        print();
    private:
        float x;
        float y;
        float z;
};

Point3d a(1,2,3);
a.print();

2.3 class 和 struct 区别

参考资料

• 浙江大学 C++ 翁恺