吴裕雄--天生自然C语言开发：错误处理

#include <stdio.h>
#include <errno.h>
#include <string.h>

extern int errno ;

int main ()
{
   FILE * pf;
   int errnum;
   pf = fopen ("unexist.txt", "rb");
   if (pf == NULL)
   {
      errnum = errno;
      fprintf(stderr, "错误号: %d\n", errno);
      perror("通过 perror 输出错误");
      fprintf(stderr, "打开文件错误: %s\n", strerror( errnum ));
   }
   else
   {
      fclose (pf);
   }
   return ;
}

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

main()
{
   int dividend = ;
   int divisor = ;
   int quotient;

   if( divisor == ){
      fprintf(stderr, "除数为 0 退出运行...\n");
      exit(-);
   }
   quotient = dividend / divisor;
   fprintf(stderr, "quotient 变量的值为 : %d\n", quotient );

   exit();
}

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

main()
{
   int dividend = ;
   int divisor = ;
   int quotient;

   if( divisor == ){
      fprintf(stderr, "除数为 0 退出运行...\n");
      exit(EXIT_FAILURE);
   }
   quotient = dividend / divisor;
   fprintf(stderr, "quotient 变量的值为: %d\n", quotient );

   exit(EXIT_SUCCESS);
}