• C

itoa function (not atoi)

I'm looking for a standard function to do integer-to-string conversion.  The comp.lang.c FAQ says to just use sprintf, but I'd rather live without that cruft.  I could swear I found just such a function once while browsing through man pages, but can't locate it again.
LVL 3
dhmAsked:
Who is Participating?

[Product update] Infrastructure Analysis Tool is now available with Business Accounts.Learn More

x
I wear a lot of hats...

"The solutions and answers provided on Experts Exchange have been extremely helpful to me over the last few years. I wear a lot of hats - Developer, Database Administrator, Help Desk, etc., so I know a lot of things but not a lot about one thing. Experts Exchange gives me answers from people who do know a lot about one thing, in a easy to use platform." -Todd S.

msmitsCommented:
Depends on your platform I guess. My borland compiler supports the following function:

  char *itoa(int value, char *string, int radix);

It is documented in the DOS reference, but mentions portability to the win16, win32 and OS/2 platforms. It also says that it is not standard available in ANSI C, ANSI C++ and UNIX.

0

Experts Exchange Solution brought to you by

Your issues matter to us.

Facing a tech roadblock? Get the help and guidance you need from experienced professionals who care. Ask your question anytime, anywhere, with no hassle.

Start your 7-day free trial
dhmAuthor Commented:
Oops, I should've specified unix.  I guess I'll have to ask again.  Thanks for the reply.
0
msmitsCommented:
After consulting a UNIX Sun Solaris system I came up with the following two from the atoi(3) man page:

  char *lltostr(long long value, char *ptr);
  char *ulltostr(unsigned long long value, char *ptr);

Otherwise a standard itoa is not very difficult:

  char *itoa(int val, char *ptr)
  {
    int sign = (val < 0) ? -1 : 1;
    char tmp[16];
    int i = 0, j = 0;

    val = sign * val;
    while (val != 0) {
      tmp[i] = (val % 10) + '0';
      val = val / 10;
      i++;
    }
    if (i == 0) {
      strcpy(ptr, "0");
    } else {
      if (sign == -1) {
        ptr[j] = '-';
        j++;
      }
      while (i != 0) {
        ptr[j] = tmp[i - 1];
        i--;
        j++;
      }
      ptr[j] = '\000';
    }
  }

While this may not be the most efficient solution or it may not even work, as I completely did this without a compiler and some test cases, it shows that the base-10 algorithm is not difficult.

Although I agree that a library function would be better, so you don't have to invent and test such trivial stuff...

0
dhmAuthor Commented:
Thanks for snooping around...I'd found the Solaris functions too, but they don't exist on the other platforms I compile for.  I ended up just writing itoa, ltoa, utoa, and ultoa:

const char *itoa( int n )
{
      static char buf[32]; /* yeech */
      sprintf( buf, "%d", n );
      return buf;
}

Now I've just gotta find out how to do thread-specific static
function data (on all those platforms).  *That* sort of thing is the hard part on library functions like this.  The logic is, as you say, trivial.
0
msmitsCommented:
There are several solutions:
1. require the caller to pass a valid character buffer

2. malloc the space and require the caller to free it

I find the first solution the 'most' clean.

0
It's more than this solution.Get answers and train to solve all your tech problems - anytime, anywhere.Try it for free Edge Out The Competitionfor your dream job with proven skills and certifications.Get started today Stand Outas the employee with proven skills.Start learning today for free Move Your Career Forwardwith certification training in the latest technologies.Start your trial today
C

From novice to tech pro — start learning today.