Create a UTF8 file without BOM with Inno Setup (Unicode version)

Question

I have to read and modify some JSON files. The file encoding must be UTF8 without BOM or the JSON file will be not accepted.

I tried the following Code:

Answer 1

Use the WideCharToMultiByte function to convert the string to UTF-8 and just save it:

const
  CP_UTF8 = 65001;

function WideCharToMultiByte(CodePage: UINT; dwFlags: DWORD;
  lpWideCharStr: string; cchWideChar: Integer; lpMultiByteStr: AnsiString;
  cchMultiByte: Integer; lpDefaultCharFake: Integer;
  lpUsedDefaultCharFake: Integer): Integer;
  external 'WideCharToMultiByte@kernel32.dll stdcall';

function GetStringAsUtf8(S: string): AnsiString;
var
  Len: Integer;
begin
  Len := WideCharToMultiByte(CP_UTF8, 0, S, Length(S), Result, 0, 0, 0);
  SetLength(Result, Len);
  WideCharToMultiByte(CP_UTF8, 0, S, Length(S), Result, Len, 0, 0);
end;

function SaveStringToUTF8FileWithoutBOM(FileName: string; S: string): Boolean;
var
  Utf8: AnsiString;
begin
  Utf8 := GetStringAsUtf8(S);
  Result := SaveStringToFile(FileName, Utf8, False);
end;

You have to use Unicode version of Inno Setup (the only version as of Inno Setup 6).

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See also:

• LoadStringFromFileInCP and LoadStringsFromFileInCP functions in:
  Inno Setup - Convert array of string to Unicode and back to ANSI
• Inno Setup replace a string in a UTF-8 file without BOM