浅谈VC中define的使用方法

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１、用来定义常数

　例子：

#define  MAXTIME 60int i;for(i =0; i < MAXTIME; i++){    //todo something}

２、定义算式`

例子：

　①

#define  COUNTOF(array) (sizeof(array) / sizeof(*array) )typedef struct{　　int num;　　char name[20];　　float score;}student;student stu[] ={　　{1001, "zhuque", 97.5},　　{1003, "zuozhu", 83 },　　{1004, "minren", 83 },　　{1007, "guaili", 78 },　　{1010, "xiaoli", 80 }};const student* FindStd(int number){    int i;    const student* std;    std = stu;    printf("sizeof(stu) = %d\n", sizeof(stu));    printf("sizeof(*stu) = %d\n", sizeof(*stu));    printf("COUNTOF(stu)=%d\n",COUNTOF(stu));    for (i = 0; i < COUNTOF(stu); i++){        printf("YES YOU CAN\n");if (std->num == number){printf("here\n");return std;}std++;}if( i >= COUNTOF(stu) ){return NULL;}}

３、用来定义函数

#include <stdio.h>int MAX(unsigned long, unsigned long, unsigned long);#define RGB88(g,b) ((g)>(b)?(g):(b))#define RGB888(r,g,b) MAX(r,g,b)int MAX(unsigned long r, unsigned long g, unsigned long b){return RGB88(r,RGB88(g,b));}int main(){unsigned long r = 100,  g = 200,  b = 300;printf("THE MAX NUMBER IS [%d]\n", RGB888(r,g,b));}

输出结果 300

４、用于结构体封装

#define GDefClass(GClassName,GSuperClass)\struct GClassName {\GSuperClass gscBase;#define GDefEnd\};typedef struct GObject{char * name;int  iId;float score;};GDefClass(GBaseWindow,GObject)short nX;short nY;short nWidth;short nHeight;GDefEnd

以上的 GDefClass(GBaseWindow,GObject)

....

GDefEnd

就相当于

struct GBaseWindow {GObject  gscBase;short nX;short nY;short nWidth;short nHeight;}

这个用法就像C++的类继承的功能，以上的用法就是实现了C中的结构体继承。