print_number() - an alternative for sprintf()

In most situations this probably falls clearly into the category of premature optimization, but if you need that extra ounce of efficiency in a situation where you're converting a numeric value into its ascii equivalent via sprintf(), you might find this print_number() solution useful.

It has precisely one feature beyond simply ascii-fying numbers, and that is adding an optional zero-padding; printing "123" with five places of zero padding results in "00123", which you could accomplish like this:

char output[6] = { 0 };
print_number(output, 123, 5);

So, here are the performance characteristics when printing 0..100,000,000 with eight-digit zero-padding (in microseconds):

int main(int, const char **).. test1=9273221, test2=22877905

That's 9.27 seconds for print_number() and 22.88 seconds for sprintf().

Oh, perhaps this could be considered a 2nd feature. print_number() returns a pointer to the char immediately following the end of the number it just printed. It saves you a step in a situation like this:

char output[n];
char *output_ptr = output;
output_ptr = print_number(output_ptr, 1, 5);
output_ptr = print_number(output_ptr, 2, 5);
output_ptr = print_number(output_ptr, 3, 5);

Etc. You don't have to explicitly increment the pointer each time since that value is returned.
Enjoy.