Allow only [a-z][A-Z][0-9] in string using PHP

Question

How can I get a string that only contains a to z, A to Z, 0 to 9 and some symbols?

Answer 1

A shortcut will be as below also:

if (preg_match('/^[\w\.]+$/', $str)) {
    echo 'Str is valid and allowed';
} else
    echo 'Str is invalid';

Here:

// string only contain the a to z , A to Z, 0 to 9 and _ (underscore)
\w - matches [a-zA-Z0-9_]+

Hope it helps!