Re: Floats and avoid exponential notation - How?

"k bah" <kbah@linuxmail.org> wrote on 07/17/2008 05:23:40 AM: > Hi, > > From http://www.php.net/manual/en/language.types.float.php > (second comment in > that page, from "kjohnson at zootweb dot com"): > > "PHP switches from the standard decimal notation to exponential notation for > certain "special" floats. > > I have the same problem. I have a big number I have to represent, it's > usually "1" followed by 10 "zeros", the biggest value I'll > have for it is 19999999999, never more than this. I only make one operation > with it, (+), most of the time I need that number as a > string, and never need it's float representation, only the absolute value (in > fact, it's never going to have a fractional part). I > cannot use integers because it's bigger than the integer range. > > If it goes to it's exponential representation, breaks my code. Users are > identified by that number. > > So, any suggestions/thoughts? > Is there a way to prevent php from using the exponential notation for a float? I don't know of any way to modify PHP's behavior with regard to this. That's not to say there isn't a way, but I don't know of one. This might be a brute force way to address it. You'll want to add additional checks so you don't end up in any infinite loops. You should definitely test with larger numbers in the range that you are actuallly using. Hope this gets you what you need: // example: one of the "special" ones, prints in exponential notation, "1.4E+6" $num = 1400000.; if(strstr($num, 'E')) { echo "yep, exp notation<br>"; list($significand, $exp) = explode('E', $num); list($void, $decimal) = explode('.', "$significand"); $decimal_len = strlen("$decimal"); $exp = str_replace('+', '', "$exp"); $exp -= $decimal_len; $append = ''; for($i = 1; $i <= $exp; $i++) { $append .= '0'; } $tmp = str_replace('.', '', "$significand"); $reconsctructed = "$tmp" . "$append"; echo '<pre>reconstructed: ', "$reconsctructed", '</pre>'; } kjohnson at zootweb dot com :)