Change special characters in array Delphi

Question

Some string that I am getting is UTF-8 encoded, and contains some special characters like Å¡, Ä‘, Ä etc. I am using StringReplace() to convert it to some normal text, but I can only convert one type of character. Because PHP also has a function to replace strings as seen here: how to replace special characters with the ones they're based on in PHP?, but it supports arrays:

<?php
  $vOriginalString = "¿Dónde está el niño que vive aquí? En el témpano o en el iglú. ÁFRICA, MÉXICO, ÍNDICE, CANCIÓN y NÚMERO.";

  $vSomeSpecialChars = array("á", "é", "í", "ó", "ú", "Á", "É", "Í", "Ó", "Ú", "ñ", "Ñ");
  $vReplacementChars = array("a", "e", "i", "o", "u", "A", "E", "I", "O", "U", "n", "N");

  $vReplacedString = str_replace($vSomeSpecialChars, $vReplacementChars, $vOriginalString);

  echo $vReplacedString; // outputs '¿Donde esta el nino que vive aqui? En el tempano o en el iglu. AFRICA, MEXICO, INDICE, CANCION y NUMERO.'
?>

How can I do this in Delphi? StringReplace doesn't support arrays.

Answer 1

function str_replace(const oldChars, newChars: array of Char; const str: string): string;
var
  i: Integer;
begin
  Assert(Length(oldChars)=Length(newChars));
  Result := str;
  for i := 0 to high(oldChars) do
    Result := StringReplace(Result, oldChars[i], newChars[i], [rfReplaceAll])
end;

If you are concerned about all the needless heap allocations caused by StringReplace then you could write it this way:

function str_replace(const oldChars, newChars: array of Char; const str: string): string;
var
  i, j: Integer;
begin
  Assert(Length(oldChars)=Length(newChars));
  Result := str;
  for i := 1 to Length(Result) do
    for j := 0 to high(oldChars) do
      if Result[i]=oldChars[j] then
      begin
        Result[i] := newChars[j];
        break;
      end;
end;

Call it like this:

newStr := str_replace(
  ['á','é','í'],
  ['a','e','i'], 
  oldStr
);

Answer 2

Getting rid of your accents is called Normalization.

Since you are using Unicode, you are not only wanting to normalize the short list of accented characters in your question. In fact you are looking for Unicode Normalization Form D (NFD) or KD (NFKD), which you can do in Windows and of course in Delphi.

This answer should get you going on the theoretical side.

This Delphi code and this answer should get you going implementing.