- str_replace: documentation ( source)
<?php
function isStringOnlyAZ($the_string)
{
$valid_chars = array('A','B','C','D','E','F','G','H','I','J','K','L','M','N','O','P','Q','R','S','T','U','V','W','X','Y','Z');
$the_string = str_replace($valid_chars, "", $the_string);
echo $the_string;
return (strlen($the_string)==0);
}
echo isStringOnlyAZ("St mary's");
?>