Re: [bug-grep] length of dec. representation of a number

[Julian Foad]

Paul Eggert wrote:
> How about if you use the standard gnulib macro for this instead of
> reinventing the wheel?  Here it is, taken from inttostr.h:
>
> /* Upper bound on the string length of an integer converted to string.
>    302 / 1000 is ceil (log10 (2.0)).  Subtract 1 for the sign bit;
>    add 1 for integer division truncation; add 1 more for a minus sign.  */
> #define INT_STRLEN_BOUND(t) ((sizeof (t) * CHAR_BIT - 1) * 302 / 1000 + 2)

We can't #include inttostr.h because (AFAIK) it's not standard in ANSI/ISO C, 
but we can certainly copy the macro definition.  That would be sensible, to 
avoid using a different name and a different definition.

Thanks for explaining the relevance of CHAR_BIT, which is that it gives the 
units of "sizeof (t)".  I was thinking that it could only refer to the size of 
the characters that hold the ASCII output of the conversion.

- Julian