Filter Text

[smerny]

How can I filter out anything besides the alphabet and numbers?

[justsomeguy]

The easiest way would probably be to use a regular expression pattern with preg_replace to replace anything not in the pattern.

[smerny]

is there a way to have a boolean on whether or not a variable contains characters that are not alphabet/number?like $name1= "JAne32j"$name2 = "sad"a function i could run on these that would be true or false depending on if it has invalid characters?

[justsomeguy]

That would be a regular expression that uses preg_match instead of preg_replace.

[smerny]

could you show me an example? i looked at preg_match on the php manual and it seems more about finding particular characters rather than making sure there are only letters and numbers.... the only way i can think of to use that would be to individually search each character that i dont want and see if it has any... but that would take many many lines...

[jeffman]

Regular expressions are more flexible than you may imagine. Consider:

$subject = "abc123";$pattern = '/[a-zA-Z0-9]/';$result = preg_match($pattern, $subject);

$result returns true because the first character of $subject matches one of the three character ranges in $pattern. This is a pretty useless regex. The one below is one you could actually use:

$subject = "abc*123"; $pattern = '/[^a-zA-Z0-9]/'; $result = preg_match($pattern, $subject);if ($result) {	// we have an illegal character}

$result returns true because the pattern is different. The ^ inside the brackets says we're looking for all characters that are NOT in the ranges. Since the * is not in any of the ranges, we have a match. It's a logic thing. We have a "match" because we found what is NOT specified in the pattern.

[smerny]

thanks for explaining that =]