Thread: string problems

Look into ctype.h's isdigit() function: http://www.hmug.org/man/3/isnumber.html
That should make your code more clean for you to easily see what to do from there.

>i would like to know how can i put a '?' at the begining of a digit sequence ended by 2.

Maybe something like this.

Code:

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

int main(void)
{
   int i;
   for ( i = 0; i < 15; ++i )
   {
      char input [ 51 ], *ptr = input + 1;
      sprintf(ptr, "%d", i); /* fake user input */
      if ( input [ strlen(input) - 1 ] == '2' )
      {
         *--ptr = '?';
      }
      puts(ptr);
   }
   return 0;
}

/* my output
0
1
?2
3
4
5
6
7
8
9
10
11
?12
13
14
*/

Dave_Sinkula says...

Maybe something like this.

Code:

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

int main(void)
{
   int i;
   for ( i = 0; i < 15; ++i )
   {
      char input [ 51 ], *ptr = input + 1;
      sprintf(ptr, "%d", i); /* fake user input */
      if ( input [ strlen(input) - 1 ] == '2' )
      {
         *--ptr = '?';
      }
      puts(ptr);
   }
   return 0;
}

I dont think so, not in C programming anyway.

Code:

for ( i = 0; i < 15; ++i )
   {
      /* illegal in C, ok in C++ */
      char input [ 51 ], *ptr = input + 1;
      sprintf(ptr, "%d", i); /* fake user input */

>I dont think so, not in C programming anyway.

Think again.

Originally Posted by bigtamscot

I dont think so, not in C programming anyway.

Code:

for ( i = 0; i < 15; ++i )
   {
      /* illegal in C, ok in C++ */
      char input [ 51 ], *ptr = input + 1;
      sprintf(ptr, "%d", i); /* fake user input */

What's so illegal about that? It's perfectly valid C.