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Digg  is_nan
Finds whether a value is not a number
(PHP 4 >= 4.2.0, PHP 5)
Code Examples / Notes » is_nanvincent
Since NaN is not even equal to itself, here is a way to test it: <?php function my_is_nan($_) { return ($_ !== $_); } ?> paul
See is_numeric if you have an older version of PHP than 4.20. It should serve your purpose well. If you're using PHP 3, you can use a regular expression: function isNaN( $var ) { return ereg ("^[0-9\.]+$", $var); } nez
Paul, i guess better would be: function isNaN( $var ) { return ereg ("^[-]?[0-9]+([\.][0-9]+)?$", $var); } darkangel
nan/"not a number" is not meant to see if the data type is numeric/textual/etc.. NaN is actually a set of values which can be stored in floating-point variables, but dont actually evaluate to a proper floating point number. The floating point system has three sections: 1 bit for the sign (+/-), an 8 bit exponent, and a 23 bit fractional part. There are rules governing which combinations of values can be placed into each section, and some values are reserved for numbers such as infinity. This leads to certain combinations being invalid, or in other words, not a number. sku
Hi nez, better would be: function isNaN( $var ) { return !ereg ("^[-]?[0-9]+([\.][0-9]+)?$", $var); } ys, Sku |
