Q47026: Second sscanf Fails After sscanf Using %i Format

Article: Q47026
Product(s): See article
Version(s): 5.10   | 5.10
Operating System(s): MS-DOS | OS/2
Keyword(s): ENDUSER | | mspl13_c
Last Modified: 26-JUL-1989

The Microsoft C 5.10 run-time function sscanf fails to scan a string
if the following conditions are met:

1. An initial sscanf using the %i format specifier is carried out on a
   string with leading white space characters.

2. A second sscanf of a string with leading white space characters
   will fail.

To work around this problem, do one of the following:

1. Change the format string "%i" to "%d".

2. Change the format string for the second and all following sscanf's so
   that it causes all leading spaces to be removed. For example, use a
   format of " %d" instead of "%d".

The following program demonstrates this problem when compiled
with Microsoft C 5.10 using default compiler options:

#include <stdio.h>

void main(void)
{
  char  *str1= "  23  ";
  char  *str2= "  99  ";
  int   val0;
  int   val1;
  int   val2;

  sscanf(str2,"%d", &val1);     /* this line works correctly */
  sscanf(str1,"%i", &val0);     /* this line works correctly */
  sscanf(str2,"%d", &val2);     /* this line will fail       */

  if(val1 != val2)
        printf("sscanf test failed \n");
  else
        printf("sscanf passed test\n");
}

Microsoft is researching this problem and will post new information as
it becomes available.

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