note 65825 deleted from control-structures.switch by bjori

Note Submitter: php dot danson at spamgourmet dot com Reason: in docs ---- Watch out if your switch value is empty! If it is, it can invert the result of an expression that returns 'false'. Example: <?php switch ($domain){ case "greentheme.net": $theme = "green"; break; case (strpos($domain,"-secure.com")!==FALSE): $theme = "gold"; break; default: $theme = "white"; break; } ?> This block takes a domain and determines the theme to use. If the domain matches greentheme.net it uses the green theme. If the domain contains "-secure.com" in it it uses the gold theme. Otherwise it uses the white theme. Now what happesn if $domain is blank ("")? 1. strpos("","-secure.com") evaluates to FALSE 2. FALSE !== FALSE evalues to FALSE 3. So you would think that this case is skipped. HOWEVER an additional step is taken! Remember that a switch statement compares the case values to the switch value. Thus it compares: 4. $domain == FALSE aka "" == FALSE which in PHP evaluates to TRUE! Thus the case block is indeed executed and the gold theme is used when the white should have. Simple solution: Make sure empty variables (or variables that evaluate to false) are never passed into a switch! Dan