PHP replacing special characters like à->a, è->e

Question

I have php document signup.php which save the content from form (in form.php document) to MySQL base. The problem arises when I want to reformat the input content. I want do

Answer 1

function correctedText($txt=''){
  $ss = str_split($txt);
    
  for($i=0; $i= 192 && $asciiNumber <= 197)$ss[$i] = 'A';
    elseif($asciiNumber == 198)$ss[$i] = 'AE';
    elseif($asciiNumber == 199)$ss[$i] = 'C';
    elseif($asciiNumber >= 200 && $asciiNumber <= 203)$ss[$i] = 'E';
    elseif($asciiNumber >= 204 && $asciiNumber <= 207)$ss[$i] = 'I';
    elseif($asciiNumber == 209)$ss[$i] = 'N';
    elseif($asciiNumber >= 210 && $asciiNumber <= 214)$ss[$i] = 'O';
    elseif($asciiNumber == 216)$ss[$i] = 'O';
    elseif($asciiNumber >= 217 && $asciiNumber <= 220)$ss[$i] = 'U';
    elseif($asciiNumber == 221)$ss[$i] = 'Y';
  }
    
  $txt = implode('', $ss);
    
  return $txt;
}