Check if a string has invalid characters

[TrueColors]

I want to allow Alphabetical strings, Numeric strings, and Alphanumeric strings. For example "Bob", "1234", "bob1234" are all valid.

 

I want to check if the string has invalid characters, return true if it does (or false, which ever method works).

 

How can I do it?

[requinix]

ctype_alnum is your friend.

[btherl]

You can probably get away with this:

 

if (ctype_alnum($string)) {
  # Yes, all alpha or numeric
}

 

Do be aware that an empty string will match because it doesn't contain any characters that are not alphanumeric, so if you don't want empty strings you'll need to check for them seperately.

[TrueColors]

New function to add to me list! Thanks!

 

Would this function return true if we had "some string" (notice the space) ?

[btherl]

It would return false.  If you want a custom character set you can do it a few ways.. one is like this:

 

if (preg_match('|^[a-zA-Z0-9 ]*$|', $string))

 

Meaning "If the string consists of any number of characters a-z A-Z 0-9 or space, then it's a match".  Again, that will match empty strings.  If you don't want empty strings you can change the * to a +, which means "one or more"

[TrueColors]

Thanks!