#25566 [Opn]: Casting of strings to integers is flawed, no checking for non numeric chars.

ID: 25566 Updated by: sniper@php.net Reported By: Jared dot Williams1 at ntlworld dot com Status: Open -Bug Type: Scripting Engine problem +Bug Type: Documentation problem PHP Version: 4.3.3 New Comment: See these manual pages: http://www.php.net/switch http://www.php.net/manual/en/types.comparisons.php Maybe the manual should explain this a bit better. Previous Comments: ------------------------------------------------------------------------ [2003-09-20 06:20:46] Jared dot Williams1 at ntlworld dot com How's this for an impossibility.. echo('a' != 0 ? 'TRUE' : 'FALSE'); echo('<br />'); echo('a' ? 'TRUE' : 'FALSE'); Outputs: FALSE TRUE ------------------------------------------------------------------------ [2003-09-20 06:08:53] Jared dot Williams1 at ntlworld dot com Oh erm, seems its not limited to switch either. :/ echo('a' == 0 ? 'YES' : 'NO'); Outputs: YES echo('3a' == 3 ? 'YES' : 'NO'); Outputs: YES echo(4 == '4a' ? 'YES' : 'NO'); Outputs: YES Surely these cant be considered equivalent. ------------------------------------------------------------------------ [2003-09-20 05:51:09] Jared dot Williams1 at ntlworld dot com The non-numeric string values are getting cast to integer value 0, which then match case 0:. $t = array(10,1,2,3,'*','+','3a', 'b'); foreach($t as $v) switch ($v) { case 10: echo('0'); break; case 1: echo('1'); break; case 2: echo('2'); break; case 3: echo('3'); break; case '*': echo('*'); break; default: echo($v); break; } Outputs: 0123*+3b as 3a gets cast to 3. so seems there is a missing a condition in the code somewhere, to see if the switched expression can actually be a numeric type. Also $t = array(10,1,2,3,'*','+','3a', 'b'); foreach($t as $v) switch ($v) { case 10: echo('0'); break; case 1: echo('1'); break; case 2: echo('2'); break; case '*': echo('*'); break; case '3a': echo('!!'); break; default: echo($v); break; } ?> Outputs: 012!!*+!!b So the case labels are getting cast too without the check. ------------------------------------------------------------------------ [2003-09-20 00:40:40] shadowfaxx at cc dot com To add to the above, it seems that the '0' case is the culprit. If you use the code below where '10' replaces '0', the weird behavior does not occur: $t = array(10,1,2,3,'*','+','a', 'b'); foreach($t as $v) switch ($v) { case 10: echo('0'); break; case 1: echo('1'); break; case 2: echo('2'); break; case 3: echo('3'); break; case '*': echo('*'); break; default: echo($v); break; } OutPut: 0123*+ab So it seems that Case 0: grabs all the cases which are of a different data type if the case expressions are not of the same type i.e. numeric and string. ------------------------------------------------------------------------ [2003-09-16 18:47:44] Jared dot Williams1 at ntlworld dot com "The first 5 array" should read "The first 4 array" ------------------------------------------------------------------------ The remainder of the comments for this report are too long. To view the rest of the comments, please view the bug report online at http://bugs.php.net/25566 -- Edit this bug report at http://bugs.php.net/?id=25566&edit=1