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Editorial Team
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Asked: 2026-06-02T02:50:57+00:00

according to : $ php -a Interactive shell php > var_dump(0 != 0); bool(false)

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according to :

$ php -a
Interactive shell

php > var_dump("0" != 0); 
bool(false)
php > var_dump(0 != null);
bool(false)
php > var_dump("0" != null);
bool(true)

can you explain why the last assertion is true ?

By the way, it is PHP cli 5.3.6.

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1 Answer

  1. Editorial Team

    This is defined in the manual page PHP type comparison tables.

    I find some of these very unintuitive. "0" == false is for example retarded since you often may have a form where the user inputs the number 0. Now you need to check if a field is set using isset instead of just doing a if($field). Also note that empty("0") == true!

    That’s why I use === to get type-checked comparisons or use a language without automatic type casts.

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