ontkenning in ereg_replace

$naam = "F.H.'tHaantje";
$text = ereg_replace("[a-zA-Z]", "",$naam);
echo "<p>$text</p>";

$naam = "F.H.'tHaantje";
$text = ereg_replace("[a-zA-Z]", "",$naam);
echo "<p>$text</p>";

<?php
$naam = "F.H. 't Haantje";

$naam = preg_replace('~[^a-zA-Z]~', '', $naam);

echo $naam;

<?php
$naam = "F.H. 't Haantje";
 
$naam = preg_replace('~[^a-zA-Z]~', '', $naam);
 
echo $naam;