Re: changing NULL behavior in PHP arithmetic

On Thu, 2010-04-15 at 09:46 +0200, cr.vegelin@gmail.com wrote: > Hi All, > > Is there an option in PHP to change the behavior of NULL in PHP functions ? > Now PHP uses NULL as a 0 (zero) for arithmetic, for example: > NULL + 6 = 6 > NULL * 6 = 0 > NULL / 6 = 0 > 6 / NULL = Division by zero > > What I need is the same behavior as #N/A (or =NA()) in Excel, where: > #N/A + 6 = #N/A > #N/A * 6 = #N/A > #N/A / 6 = #N/A > 6 / #N/A = #N/A > > because arithmetic operations with "Unknown" operands should result to > "Unknown" ... > > TIA, Cor You can't really, because PHP is a loosely typed language, which means it silently converts values as required by the situation. When you use mathematical operators, PHP converts the values to numbers, and NULL maps to a 0 (as does the boolean false and an empty string) The only way I can see to fix your problem is to check the value of the variables you are working on with something like is_int() Thanks, Ash http://www.ashleysheridan.co.uk