Why does this preg_match code fail?

[php_guy]

Here's my code:

 

I'm trying to make a function that returns true if the supplied string contains illegal characters, or false otherwise.

 

I can't get it to work. Could someone please comment?

 

<?phpfunction contains_illegal_chars($value) {if ( preg_match("['=]", $value) > 0 ) { 	return true; } return false;}$value = "this contain both illegal characters: ' and =" . "<BR>";echo "Value is: $value";if( contains_illegal_chars($value) )echo "yes";elseecho "no";  // This is always being returned! Even though the string clearly contains both the quote and the equals sign!?>

 

 

[BlueSkyIS]

Don't forget the slashes in the pattern:

 

 

if ( preg_match("/['=]/", $value) > 0 ) 

 

[php_guy]

Great! Thank you that worked.

 

Why do the brackets need to be escaped? Aren't they automatically treated as a regex special character? I would think you would only need to escape them if you actually wanted to search for the bracket itself.

 

So

preg_match( "[/[]", $value)

 

No?

[jcbones]

The slashes as advised are de-limiters, any non-alphanumeric character can be a de-limiter.  Such as ~,!,@,%,etc.  Just remember, a de-limiter that is used inside the expression, must be escaped.