Remove special character in php

 <?php

$str = 'today I \'ll learn PHP and the day with awsome.';

$str1 = 'This is a bad command so donot put here  : del c:\\*.*';

echo RemoveSpecialChar($str);

echo "<br/>";

echo RemoveSpecialCharinphp($str1);

function RemoveSpecialCharinphp($str)

{

    $string1= preg_replace('/[0-9\@\.\;\""]+/', '', $str);

    return $string1;

}

?> 

Out put of the code

1) today I 'll learn PHP and the day with awsome

2) This is a bad command so donot put here : del c:\**