Re: Stuck... Long day I think.. ;-)

On Fri, 2003-05-16 at 19:53, Frappy John wrote: > > > One general rule of thumb is never to test a floating > > > point number for equality. Still stumped with this... Tried as everyone suggested by converting to int by using *10 but still nada. Does PHP have a cast construct like C++ ?? for($i = 1; $i <= 2.1; $i += 0.1) { $p_val[] = $i; } echo "Protien (pr/kg/bodyweight):\n"; echo '<select name="protein">'."\n"; foreach($p_val as $v) { $str = (($v * 10) != ($_POST['protein'] * 10)) ? "<option value=\"$v\">" . sprintf("%.1f", $v) . "g</option>" : "<option value=\"$v\" selected=\"selected\">" . sprintf("%.1f", $v) . "g</option>"; echo $str ."\n"; } echo "</select>\n"; I still can not get ((($v * 10) != ($_POST['protein'] * 10)) to evaluate as false. I set up another loop to see what was going on foreach($p_val as $v) echo '$v= ' . $v * 10 . ' - $_POST[\'protein\']= " . $_POST['protein'] * 10 . "\n"; which returns $v= 10 - $_POST['protein']= 13 $v= 11 - $_POST['protein']= 13 $v= 12 - $_POST['protein']= 13 $v= 13 - $_POST['protein']= 13 $v= 14 - $_POST['protein']= 13 $v= 15 - $_POST['protein']= 13 $v= 16 - $_POST['protein']= 13 $v= 17 - $_POST['protein']= 13 $v= 18 - $_POST['protein']= 13 $v= 19 - $_POST['protein']= 13 $v= 20 - $_POST['protein']= 13 so I do not see why I can not check $v against $_POST['protein'] at this point... > > > > Ah, I did not know that, thanks. So any suggestions for > > how to approach this then? I guess I need to convert > > those values to something else and test them?? > > Right. Probably best to convert to integers (multiply by > ten) and convert back for display. You could test the > floating point for a range instead, but I think the > simplest and fastest is to use integers. > > For more, see the box labeled: > "Floating point precision" at: > > http://www.php.net/manual/en/language.types.float.php > > --Frappy. > > On Friday 16 May 2003 07:43 pm, Brian V Bonini wrote: > > On Fri, 2003-05-16 at 19:19, Frappy John wrote: > > > > I do the same thing here and it works fine: > > > > > > > > for($i = 250; $i <= 1000; $i += 250) { > > > > $c_val[] = $i; > > > > } > > > > > > . . . > > > > > > > I'm not seeing the difference in terms of > > > > functionality. > > > > > > One big difference is your protein routine deals with > > > decimals (floating point) and your calories routine > > > deals with whole numbers (integers). > > > > > > One general rule of thumb is never to test a floating > > > point number for equality. > > > > Ah, I did not know that, thanks. So any suggestions for > > how to approach this then? I guess I need to convert > > those values to something else and test them?? > > > > > > I can not get ($v != $_POST['protein']) to evaluate > > > > as true. > > > > > > I would think it would *always* evaluate as true (i.e. > > > always != ). Is that what you meant to say? > > > > Yup, that's what I meant, like I said, "long day"... ;-)