It could also be seen: null == 0 null(0) + null(0) == 0 JK > On Sep 4, 2023, at 3:51 PM, Ashley Sheridan <ash@xxxxxxxxxxxxxxxxxxxx> wrote: > > > On 04/09/2023 05:35, tyamahori wrote: >> Dear PHP users. >> >> I have questions about the behavior `null + null = 0`. >> >> Since PHP4.3.0, `null + null` becomes `0`. >> https://3v4l.org/YX3Od#veol >> >> Form php-src, >> https://github.com/php/php-src/blob/e2189e5f376092eeaeb4c06ff9b5918bfc016917/Zend/zend_operators.c#L325 >> >> It seems _zendi_try_convert_scalar_to_number converts null to 0. >> >> Do you know who decided this behavior ? >> Do you know how did this behavior come about? >> >> Regards. >> Kazuki >> >> > What you're looking at here is type coercian, or as PHP refers to it, type juggling. > > You're using a non-numerica type as a number when you use the + operator. This has the effect of casting null first to an int, which results in your calculation becoming 0 + 0. > > More details on PHPs type juggling can be found at https://www.php.net/manual/en/language.types.type-juggling.php > > Thanks, > Ash > > -- > www.ashleysheridan.co.uk
