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

[Luigi S. <gi...@li...>]

Hello,

I've revised the previous implementation of "itoa", adding the
enhancements that Per Westmark suggested. The code lacks error
checking, so isn't robust at all. 

--
>> gisan >>



t_itoa.c
--------
#include <stdio.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:\tk = %d\n", k);
  printf("OUTPUT:\ts = %s\n\n", s);

  k = -4567; /* a little harder: using a negative number */
  s = itoa(k);
  printf("INPUT:\tk = %d\n", k);
  printf("OUTPUT:\ts = %s\n\n", 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);

#endif /* not itoa_h */
------


itoa.c
------
#include "itoa.h"
#define MAXSZ   21  /* assuming integer is made of 19 digits + sign */ 

char *
itoa(int n)
{
  static char buf[MAXSZ]; 
  char *p = buf + MAXSZ; /* sweep across buffer */
  char neg = 0;  /* 1 means that the integer is negative */

  if (n < 0) /* negative integer */
    {
      n = -n;  /* work on its absolute value */
      neg = 1; /* turn on the flag */
    }

  *p = '\0'; /* terminate string */

  while (n && p > buf)  /* main loop */
    {
      *--p = '0' + n % 10; /* char for a digit as offset from '0' */
      n /= 10; /* drop last character */
    }

  if (neg && p > buf ) /* prepend a negative sign */
    *--p = '-';
  
  return p;
}
------