how to check and remove leading zeroes from the buffer using c program

amit_pansuria · 11-11-2008, 10:43 AM

Helo ,
I m writing small module of c.on RHEL 4

I have one buffer (for e.g. buffer = "002"
now I want to check whethere buffer contains leading zeroes and if it contains
leading zeroes then I want to remove all leading zeroes
( i.e. if buffer = "002" then I want to make buffer = "2")

how do I do using c code

Regards,
Amit

tronayne · 11-11-2008, 11:04 AM

Easy way? Try using strtol() and sprintf(), something like this

Code:

int     value;

/*     get what's in buf as a number     */
value = (int) strtol (buf, (char **) NULL, 10);
/*     copy it back     */
(void) sprintf (buf, "%d", value);

You can also do that all in one whack; replace "value" in the sprintf with the strtol.

You can also use the atoi() function (the strtol() function is more complicated):

Code:

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

main    ()
{
        char    buf [BUFSIZ];

        (void) sprintf (buf, "002");
        (void) fprintf (stdout, "%d\n", atoi (buf));
}

dwhitney67 · 11-11-2008, 05:32 PM

Another option, is to use strtok().

PHP Code:



  // check if leading zero exists 
  if (buf[0] == '0') 
  { 
    // remove leading zero(es) 
    sprintf(buf, "%s", strtok(buf, "0")); 
  }

Sergei Steshenko · 11-11-2008, 05:39 PM

Quote:

Originally Posted by dwhitney67

Another option, is to use strtok().

PHP Code:



  // check if leading zero exists 
  if (buf[0] == '0') 
  { 
    // remove leading zero(es) 
    sprintf(buf, "%s", strtok(buf, "0")); 
  }

Well, probably doesn't matter in this case, but 'sprintf' is slow compared to memmove + strlen.

estabroo · 11-11-2008, 06:31 PM

or something really simple

Code:

        char    buf [BUFSIZ];
        char*   p = buf;
        char*   e = buf+BUFSIZ;
...
        while ((p < e) && (*p == '0') {
          p++;
        }
...
}