typdef

 

/*

 1.作用：给已经存在的类型起一个新的名称

 

 2.使用场合：

 1> 基本数据类型

 2> 指针

 3> 结构体

 4> 枚举

 5> 指向函数的指针

 */

 

#include <stdio.h>

 

typedef int MyInt;

typedef MyInt MyInt2;

 // 给指针类型char *起一个新的类型名称String

typedef char * String;

 

/*

struct Student

{

    int age;

};

typedef struct Student MyStu;

*/

 

/*

typedef  struct Student

{

    int age;

} MyStu;

*/

 

 

typedef struct

{

    int age;

} MyStu;

 

/*

enum Sex {Man, Woman};

typedef enum Sex MySex;

*/

 

typedef enum {

    Man,

    Woman

} MySex;

 

 

typedef int (*MyPoint)(int, int);

 

int minus(int a, int b)

{

    return a - b;

}

 

int sum(int a, int b)

{

    return a + b;

}

/*

struct Person

{

    int age;

};

 

typedef struct Person * PersonPoint;

*/

 

typedef struct Person

{

    int age;

} * PersonPoint;

 

int main()

{

    // 定义结构体变量

    struct Person p = {20};

    

    PersonPoint p2 = &p;

    

    //struct Person *p2 = &p;

     //MyPoint p = sum;

    //MyPoint p2 = minus;

    //int (*p)(int, int) = sum;

    

    //int (*p2)(int, int) = minus;

    

    //p(10, 11);

    

    

    //MySex s = Man;

    //enum Sex s = Man;

    //enum Sex s2 = Woman;

    // struct Student stu3;

    //MyStu stu = {20};

    //MyStu stu2= {21};

    

    return 0;

}

 

void test2()

{

    String name = "jack";

    

    printf("%s\n", name);

}

 

void test()

{

    int a;

    MyInt i = 10;

    MyInt2 c = 20;

    

    MyInt b1, b2;

    

    printf("c is %d\n", c);

}