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From: dankg@monsoon.Berkeley.EDU (Dan KoGai)
Newsgroups: comp.lang.c
Subject: Re: integer to string function (itoa())
Message-ID: <1990Jun30.071229.23965@agate.berkeley.edu>
Date: 30 Jun 90 07:12:29 GMT
References: <22888@boulder.Colorado.EDU> <153@travis.csd.harris.com>
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Reply-To: dankg@monsoon.Berkeley.EDU (Dan KoGai)
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In article <153@travis.csd.harris.com> brad@SSD.CSD.HARRIS.COM (Brad Appleton) writes:
>In article <22888@boulder.Colorado.EDU> baileyc@tramp.Colorado.EDU (BAILEY CHRISTOPHER R) writes:
>
>>Help, I need an itoa() function for use with my Sun compiler.
>
>Perhaps I missed something but ...  Is there some reason why:
>
>  int i = 10; char a[3];
>  sprintf( a, "%d", i );
>
>is unnacceptable for your purposes?

	Maybe.  But I was wondering why there's no itoa() in most C libraries:
atoi() exists and often used in scanf().  Why do we let [sf]printf() do
all conversion instead of calling itoa...

	itoa() would be not that hard to program.  Let me make it up:

/*
 * itoa.c
 * converts integer to ascii string
 */

char *itoa(int i)
/* or
 * char
 * itoa(i)
 * int i;
 */
{
  static char buf[16]; /* twelve will suffice including sign but hell */
  char *bufptr = &buf[15]; /* bufptr pts at the end of buf */
  char sign = 0;/* true if negative */
  *bufptr-- = 0;/* terminate string for sure */
  if (i < 0) {
    sign = 1;	/* set negative */
    i = -i;	/* i must be positve for do-while loop */
  } 
  do{	/* while fails if i = 0 */
    *bufptr-- = i % 10 + '0'; /* sets digit from low to high */
    i /= 10;/* shift one digit */
  }while(i != 0);
  if (sign) {
    *bufptr = '-';	/* if negative put '-' */
    return bufptr;
  }
  else return ++bufptr;	/* rewind overrun bufptr */
}

/* main() for test */
main(int argc, char **argv){
  int i = atoi(argv[1]);
  printf("via printf:%d via itoa:%s\n", i, itoa(i));
}

	This should work unless your character table is so wierd that it
doesn't have [0-9] consecutively