How do I limit the size of a string

[Anon]

I would like to take a string (of any length) and only use the first 20 characters.

I would like to take $test and change it so if there is more than 20 characters the rest are taken off and $test is then resaved as the result.

There must be a function to do this but I can't find it.

[Anon]

string substr(string string, int start, int [length])

$test = substr($test, 0, 20);