C语言条件编译详解

复制纯文本新窗口

1. #include <stdio.h>
2. #define NUM ok
3. int main(void){
4. struct stu{
5. int num;
6. char *name;
7. char sex;
8. float score;
9. } *ps;
10. ps=(struct stu*)malloc(sizeof(struct stu));
11. ps->num=102;
12. ps->name="Zhang ping";
13. ps->sex='M';
14. ps->score=62.5;
15. #ifdef NUM
16. printf("Number=%d\nScore=%f\n",ps->num,ps->score);
17. #else
18. printf("Name=%s\nSex=%c\n",ps->name,ps->sex);
19. #endif
20. free(ps);
21. return 0;
22. }

#include <stdio.h>
#define NUM ok
int main(void){
    struct stu{
        int num;
        char *name;
        char sex;
        float score;
    } *ps;
    ps=(struct stu*)malloc(sizeof(struct stu));
    ps->num=102;
    ps->name="Zhang ping";
    ps->sex='M';
    ps->score=62.5;
    #ifdef NUM
        printf("Number=%d\nScore=%f\n",ps->num,ps->score);
    #else
        printf("Name=%s\nSex=%c\n",ps->name,ps->sex);
    #endif
    free(ps);
    return 0;
}

复制纯文本新窗口

1. #define NUM

#define NUM

复制纯文本新窗口

1. #include <stdio.h>
2. #define R 1
3. int main(void){
4. float c,r,s;
5. printf ("input a number: ");
6. scanf("%f",&c);
7. #if R
8. r=3.14159*c*c;
9. printf("area of round is: %f\n",r);
10. #else
11. s=c*c;
12. printf("area of square is: %f\n",s);
13. #endif
14. return 0;
15. }

#include <stdio.h>
#define R 1
int main(void){
    float c,r,s;
    printf ("input a number:  ");
    scanf("%f",&c);
    #if R
        r=3.14159*c*c;
        printf("area of round is: %f\n",r);
    #else
        s=c*c;
        printf("area of square is: %f\n",s);
    #endif
    return 0;
}