unix/homework/scanfprob.c

   1 /*
   2  * Compile with:
   3  * gcc scanfprob.c -o scanfprob -Wall -W -Wextra -ansi -pedantic
   4  */
   5
   6 #include <stdio.h>
   7 #include <stdlib.h>
   8
   9 int main(void)
  10 {
  11     int a, rv;
  12
  13     /*
  14      * When scanf is attempting to convert numbers, any non-numeric characters
  15      * it encounters terminate the conversion and are left in the input stream.
  16      * Therefore, unexpected non-numeric input ``jams'' scanf again and again.
  17      * E.g.
  18      *
  19      * do {
  20      *     printf("Input: ");
  21      *     scanf("%d", &a);
  22      * } while (a != -1);
  23      *
  24      * See also: http://c-faq.com/stdio/scanfjam.html
  25      */
  26
  27     /* The correct way to do it */
  28     do {
  29         printf("Input: ");
  30         rv = scanf("%d", &a);
  31         if (rv == 0)
  32             scanf("%[^\n]");
  33     } while (a != -1);
  34
  35     return EXIT_SUCCESS;
  36 }