Replace French orthography to Normal English. I used this to rename folder-name/file-names/slugs

replace_french_chars.php

function frenchChars($string)
{
  $normalizeChars = array(
    'Š'=>'S', 'š'=>'s', 'Ð'=>'Dj','Ž'=>'Z', 'ž'=>'z', 'À'=>'A', 'Á'=>'A', 'Â'=>'A', 'Ã'=>'A', 'Ä'=>'A',
    'Å'=>'A', 'Æ'=>'A', 'Ç'=>'C', 'È'=>'E', 'É'=>'E', 'Ê'=>'E', 'Ë'=>'E', 'Ì'=>'I', 'Í'=>'I', 'Î'=>'I',
    'Ï'=>'I', 'Ñ'=>'N', 'Ń'=>'N', 'Ò'=>'O', 'Ó'=>'O', 'Ô'=>'O', 'Õ'=>'O', 'Ö'=>'O', 'Ø'=>'O', 'Ù'=>'U', 'Ú'=>'U',
    'Û'=>'U', 'Ü'=>'U', 'Ý'=>'Y', 'Þ'=>'B', 'ß'=>'Ss','à'=>'a', 'á'=>'a', 'â'=>'a', 'ã'=>'a', 'ä'=>'a',
    'å'=>'a', 'æ'=>'a', 'ç'=>'c', 'è'=>'e', 'é'=>'e', 'ê'=>'e', 'ë'=>'e', 'ì'=>'i', 'í'=>'i', 'î'=>'i',
    'ï'=>'i', 'ð'=>'o', 'ñ'=>'n', 'ń'=>'n', 'ò'=>'o', 'ó'=>'o', 'ô'=>'o', 'õ'=>'o', 'ö'=>'o', 'ø'=>'o', 'ù'=>'u',
    'ú'=>'u', 'û'=>'u', 'ü'=>'u', 'ý'=>'y', 'ý'=>'y', 'þ'=>'b', 'ÿ'=>'y', 'ƒ'=>'f',
    'ă'=>'a', 'î'=>'i', 'â'=>'a', 'ș'=>'s', 'ț'=>'t', 'Ă'=>'A', 'Î'=>'I', 'Â'=>'A', 'Ș'=>'S', 'Ț'=>'T',
  );

  $string = strtr($string, $normalizeChars); /* Translating the letters */ /* This function will search the key (array-key of second parameter) and will replace with its respective value. */

  $search = explode(",","ç,æ,œ,á,é,í,ó,ú,à,è,ì,ò,ù,ä,ë,ï,ö,ü,ÿ,â,ê,î,ô,û,å,ø,Ø,Å,Á,À,Â,Ä,È,É,Ê,Ë,Í,Î,Ï,Ì,Ò,Ó,Ô,Ö,Ú,Ù,Û,Ü,Ÿ,Ç,Æ,Œ");

  $replace = explode(",","c,ae,oe,a,e,i,o,u,a,e,i,o,u,a,e,i,o,u,y,a,e,i,o,u,a,o,O,A,A,A,A,A,E,E,E,E,I,I,I,I,O,O,O,O,U,U,U,U,Y,C,AE,OE");

  $string = str_replace($search, $replace, $string); /* Replacing the letters */
  
  return $string;
}