运行此代码时,为什么会出现分段错误？

Question

我正在学习使用switch语句并使用rand()和srand()函数,但是当我尝试运行这本代码时,我得到了一个分段错误,我从这本书中学到了我正在学习C语言.可能导致这种情况发生的原因是什么？

#include <stdio.h>

int main(void)
{

int iRandomNum = 0;
srand(time());

iRandomNum = (rand() % 4) + 1;

printf("\nFortune Cookie - Chapter 3\n");

  switch (iRandomNum) {

   case 1:
      printf("\nYou will meet a new friend today.\n");
      break;
   case 2:
      printf("\nYou will enjoy a long and happy life.\n");
      break;
   case 3:
      printf("\nOpportunity knocks softly. Can you hear it?\n");
      break;
   case 4:
     printf("\nYou'll be financially rewarded for your good deeds.\n");
      break;

  } //end switch

printf("\nLucky lotto numbers: ");
printf("%d ", (rand() % 49) + 1);
printf("%d ", (rand() % 49) + 1);
printf("%d ", (rand() % 49) + 1);
printf("%d ", (rand() % 49) + 1);
printf("%d ", (rand() % 49) + 1);
printf("%d\n", (rand() % 49) + 1);

} //end main function

Answer 1

这是因为time()需要一个参数,编译器会告诉你是否打开了所有警告,例如gcc -Wall -Wextra ....

不包括time.h(意味着time()获得默认原型)和不带参数调用它的组合是您的具体问题.

使用higehr警告级别时发现的问题的完整列表如下:

• time(),srand()并rand()没有原型,你需要#include两个stdlib.h和time.h.
• time()需要一个参数,比如srand (time (0)).
• 您应该返回从东西main(不是绝对必要在非常近的语言重复,但还是不错的做法).

以下更改可以正常工作:

#include <stdio.h>
#include <stdlib.h>
#include <time.h>

int main (void) {
    int iRandomNum = 0;
    srand (time (0));

    iRandomNum = (rand() % 4) + 1;

    printf("\nFortune Cookie - Chapter 3\n");

    switch (iRandomNum) {
        case 1:
            printf("\nYou will meet a new friend today.\n");
            break;
        case 2:
            printf("\nYou will enjoy a long and happy life.\n");
            break;
        case 3:
            printf("\nOpportunity knocks softly. Can you hear it?\n");
            break;
        case 4:
            printf("\nYou'll be financially rewarded for your good deeds.\n");
            break;
    } //end switch

    printf("\nLucky lotto numbers: ");
    printf("%d ", (rand() % 49) + 1);
    printf("%d ", (rand() % 49) + 1);
    printf("%d ", (rand() % 49) + 1);
    printf("%d ", (rand() % 49) + 1);
    printf("%d ", (rand() % 49) + 1);
    printf("%d\n", (rand() % 49) + 1);

    return 0;
}