Re: Weirdness with GTK+-1.2.8 ?

[Havoc Pennington <hp redhat com>]

Wolfgang Sourdeau <wolfgang ultim net> writes:
> 1.000000 1
> 
> Gtk-CRITICAL **: file gtkprogress.c: line 518
> (gtk_progress_set_percentage): assertion `percentage >= 0 &&
> percentage <= 1.0' failed.

Note that the warning is on the next iteration, so 1.0000 plus 0.02 or
whatever.
 
> I can't understand why (perc < 1.0) when perc = 1.000000.

This is because floating point doesn't have infinite precision; it's
probably stored as .999999999999999 or something, and printf rounds it
up. You can never rely on equality meaning anything for floating point
numbers, except:
 float a = 34.234;
 float b;
 b = a;
 assert (a == b); /* here a and b have the same bit pattern */

As soon as you do any arithmetic though, all bets are off:
 a += 0.3;
 a -= 0.3;
 /* a may well not be equal to its original value. */

> And if perc < 1.0, why does GTK+ complain that percentage is not <= 1.0.
> 

The warning is for 1.02 I think.

Havoc