C++第一篇--类的引入

C++第一篇--类的引入

1. 用C语言输出两个人的信息

Person1.c：通过字符实现

#include <stdio.h>

int main(int argc,int **argv)
{
    char *zs_name = "zhangsan";
    int zs_age = 10;
    char *ls_name = "lisi";
    int ls_age = 16;
    printf("name=%s,age=%d\n",zs_name,zs_age);
    printf("name=%s,age=%d\n",ls_name,ls_age);
}

Person2.c：通过数组实现

#include <stdio.h>

int main(int argc, char **argv)
{
    char *names[] = {"zhangsan", "lisi"};
    char ages[] = {10, 16};
    char *work[] = {"teacher", "doctor"};
    int i;

    for (i = 0; i < 2; i++)
    {
        printf("name = %s, age = %d\n", names[i], ages[i]);
    }
    return 0;
}

Person3-1.c：通过结构体实现

#include <stdio.h>

struct person{
    char *name;
    char age;
    char *work;
};

int main(int argc,int **arcv)
{
    struct person Person[] = {
        {"zhangsan",18,"Teacher"},
        {"lisi",29,"Doctor"},
    };
    int i;
    for(i = 0;i<2;i++)
    {
        printf("name is %s,age is %d,work is %s\n",Person[i].name,Person[i].age,Person[i].work);
    }
    return 0;
}

Person3-2.c：通过结构体实现，并在结构体实现打印函数

#include <stdio.h>

struct person{
    char *name;
    char age;
    char *work;
    
    void (*printInfo)(struct person *per); //C中结构体只可以实现函数指针
};

void printInfo(struct person *per)
{
    printf("name is %s,age is %d,work is %s\n",per->name,per->age,per->work);
}

int main(int argc,int **arcv)
{
    struct person Person[] = {
        {"zhangsan",18,"Teacher",printInfo},
        {"lisi",29,"Doctor",printInfo},
    };

    Person[0].printInfo(&Person[0]);
    Person[1].printInfo(&Person[1]);

    return 0;
}

2. 引入C++类

• 为了程序的简洁，现在用C++类实现，十分直观简单

• C++对结构体进行的扩展，不仅可以直接实现函数，还可以直接访问结构体的属性，故引入C++类

Person4.cpp

#include <stdio.h>
class person{
public:
    char *name;
    char age;
    char *work;
    void printInfo(void)
    {
        printf("name is %s,age is %d,work is %s\n",name,age,work);
    }
};


int main(int argc,int **arcv)
{
    struct person Person[] = {
        {"zhangsan",18,"Teacher"},
        {"lisi",29,"Doctor"},
    };

    Person[0].printInfo();
    Person[1].printInfo();

    return 0;
}

3. 展望

• 接下来会开始写关于面向对象编程

  • 封装
  • 继承
  • 多态

• 以上所有代码直接在Ubuntu下编译执行即可，之后代码也是如此

//C语言编译执行命令
gcc Person.c -o Person
./Person

//C++语言编译执行命令
g++ Person.c -o Person
./Person