note 30372 modified in faq.html by felipe

I do not think you are right about not being able to specify something for the value attribute, but I can see where you would have thought it would fail: A fair warning about testing to see if a variable exists... when it comes to strings, the values '' and '0' are interpreted as false when tested this way... <?php if ($string) { ... } //false for $string == '' || $string == '0' ?> The best practice for testing to see if you received a variable from the form (which in the case of a checkbox, only happens when it is checked) is to test using this... <?php if ( isSet($string) ) { ... } //true if and only if the variable is set ?> The function tests to see if the variable has been set, regardless of its contents. By the way, if anyone's curious, when you do make a checkbox without specifying the value attribute, the value sent from the form for that checkbox becomes 'on'. (That's for HTML in general, not PHP-specific). --was-- I do not think you are right about not being able to specify something for the value attribute, but I can see where you would have thought it would fail: A fair warning about testing to see if a variable exists... when it comes to strings, the values '' and '0' are interpreted as false when tested this way... <?php if ($string) { ... } //false for $string == ‘’ || $string == ‘0’ ?> The best practice for testing to see if you received a variable from the form (which in the case of a checkbox, only happens when it is checked) is to test using this... <?php if ( isSet($string) ) { ... } //true if and only if the variable is set ?> The function tests to see if the variable has been set, regardless of its contents. By the way, if anyone's curious, when you do make a checkbox without specifying the value attribute, the value sent from the form for that checkbox becomes “on”. (That's for HTML in general, not PHP-specific). http://php.net/manual/en/faq.html.php