Re: [Dev-C++] integer to string

[Per W. <pw...@ia...>]

Your implementation of itoa would leak memory - normally itoa would use a
static buffer that is overwritten at each call.

A better itoa would build the buffer from the end, i.e. *p-- = ch
thereby removing need for reversing the string.

/Per W

On Tue, 1 Apr 2003, Luigi Santillo wrote:

> On Tue, Apr 01, 2003 at 02:42:48AM +0000, Khalid El-Kary wrote:
> > Hi fellows,
> >
> > I'm wondering if there's a possible way to turn an integer to its string
> > representation in C
> >
> > //I want to get a string "5" out of f
> > int f=5;
> >
> > thanx in advance.
> >
> > Regards,
> > Khalid Al-Kary
> >
>
> Hello Khalid,
>
> You have already been supplied with an excellent solution, here is
> another approach, both: less efficient and less elegant; but I'm posting
> it anyway because I feel it is an example some newbies (like me) can
> probably benefit from.
>
> t_itoa.c
> --------
> #include <stdio.h>
> #include <stdlib.h>
> #include "itoa.h"
>
> /********************************************************************/
> int
> main()
> {
>   int k = 123;       /* integer value to be converted */
>   char *s = itoa(k); /* string holding the converted value */
>
>   printf("INPUT:\nk = %d\n\n", k);
>   printf("OUTPUT:\ns = %s\n\n", s);
>   free(s); /* return memory to the system, as soon as you can */
>
>   k = -4567; /* a little harder: using a negative number */
>   s = itoa(k);
>   printf("INPUT:\nk = %d\n\n", k);
>   printf("OUTPUT:\ns = %s\n\n", s);
>   free(s);
>
>   return 0;
> }
> --------
>
>
>
>
>
> itoa.h
> ------
> #ifndef itoa_h
> #define itoa_h
> #pragma defs_in itoa.c  /* needed by makefile generator (ignore it) */
> /********************************************************************/
>
> /* turn an integer into a string (i.e. an array) */
> char *
> itoa(int n);
>
> /* invert order of elements in an array */
> char *
> invert(char *s);
>
> /********************************************************************/
> #endif /* not itoa_h */
> ------
>
>
>
>
> itoa.c
> ------
> #include <stdlib.h>
> #include <assert.h>
> #include <string.h>
> #include "itoa.h"
>
> #define MAXSZ   21  /* assuming integer is made of 19 digits + sign */
> /********************************************************************/
> char *
> itoa(int n)
> {
>   char * buf = (char *)calloc(MAXSZ, sizeof(char)); /* get memory */
>   char *p = buf; /* pointer used to sweep across buffer */
>   char neg = 0;  /* 1 means that the integer is negative */
>
>   assert(buf != 0); /* check if memory was allocated */
>
>   if (n < 0) /* negative integer */
>     {
>       n = -n;  /* work on its absolute value */
>       neg = 1; /* turn on the flag */
>     }
>
>   while (n)  /* main loop */
>     {
>       *p++ = '0' + n % 10; /* char for a digit as offset from '0' */
>       n /= 10; /* drop last character */
>     }
>
>   if (neg) /* append a negative sign */
>     *p++ = '-';
>
>   *p = '\0'; /* terminate string */
>   return invert(buf);
> }
>
> /********************************************************************/
> char *
> invert(char *s)
> {
>   char *p = s + strlen(s); /* points the terminating '\0' */
>   char *q = s - 1;         /* points one before first char */
>
>   while (--p > ++q)
>     {
>       char c = *p; /* classic code used to swap characters */
>       *p = *q;
>       *q = c;
>     }
>
>   return s;
> }
> ------
>
>
> Regards
> --
> >> gisan >>
>
>
> -------------------------------------------------------
> This SF.net email is sponsored by: ValueWeb:
> Dedicated Hosting for just $79/mo with 500 GB of bandwidth!
> No other company gives more support or power for your dedicated server
> http://click.atdmt.com/AFF/go/sdnxxaff00300020aff/direct/01/
> _______________________________________________
> Dev-cpp-users mailing list
> Dev...@li...
> TO UNSUBSCRIBE: http://www.noicys.cjb.net/devcpp/ub.htm
> https://lists.sourceforge.net/lists/listinfo/dev-cpp-users
>