I'm currently working with a SPC that supports ANSI C, but uses its own flavour of the GNU compiler, which doesn't compile any variadic functions and things like itoa. So using sprintf & co. isn't an option for converting integers to strings. Can anyone guide me to a site where a robust, sprintf- free implementation of itoa is listed or post a suitable algorithm here? Thanks in advance.
+2
A:
This is from K&R:
void itoa(int n, char s[])
{
int i, sign;
if ((sign = n) < 0) /* record sign */
n = -n; /* make n positive */
i = 0;
do { /* generate digits in reverse order */
s[i++] = n % 10 + '0'; /* get next digit */
} while ((n /= 10) > 0); /* delete it */
if (sign < 0)
s[i++] = '-';
s[i] = '\0';
reverse(s);
}
reverse() just reverses a string.
Alok
2010-01-26 08:35:28
Use this version with care as it can overflow the buffer.
R Samuel Klatchko
2010-01-26 08:39:58
Yes, that's true. The caller has to know if the buffer has enough space or not. Just like `sprintf()`.
Alok
2010-01-26 08:42:08
Which is why you should never use `sprintf()` and only use `snprintf()`
R Samuel Klatchko
2010-01-26 08:48:37
I agree with you, if you replace "never" with "almost never". In general, one should prefer `snprintf()`. But if one is sure that the target buffer has the required size, `sprintf()` is fine too. See http://stackoverflow.com/questions/1996374/convert-integer-into-an-array/1996500#1996500 for example.
Alok
2010-01-26 09:14:05
A:
Just for the sake of completeness and as a reference for others that may stumble upon the subject, I added this link to a recursive implementation of itoa http://stackoverflow.com/questions/1993571/itoa-recursively which I like because of its simple beauty, but can't use for my target system.
NullAndVoid
2010-01-26 12:03:21