Base64 to Binary (Delphi) - delphi

Question

I used Binary to Base64 function that you answered :
Binary to Base64 (Delphi)
I successfully encode a file to base64 string and write it to MsSQL2008 database, but i want to ask a question:
How can i write this file to disk again with using EncdDecd.pas?

Answer 1

As always, David answered sufficiently. Although I can't resist to give a slightly different solution using some of the goodies from the recent Delphi versions.
procedure DecodeFile(const base64: AnsiString; const FileName: string);
var
stream: TBytesStream;
begin
stream := TBytesStream.Create(DecodeBase64(base64));
try
stream.SaveToFile(Filename);
finally
stream.Free;
end;
end;

Answer 2

This function will take a base64 encoded string, decode it, and write the resulting byte array to a file.
procedure DecodeToFile(const base64: AnsiString; const FileName: string);
var
stream: TFileStream;
bytes: TBytes;
begin
bytes := DecodeBase64(base64);
stream := TFileStream.Create(FileName, fmCreate);
try
if bytes<>nil then
stream.Write(bytes[0], Length(Bytes));
finally
stream.Free;
end;
end;
To explain what is happening here, the first line
bytes := DecodeBase64(base64);
performs the decode and returns the decoded binary contents of the file in a TBytes variable. TBytes is simply an array of bytes.
The next step is to create the file. The idiomatic way to write files in Delphi is to use streams. In this case we want a TFileStream.
stream := TFileStream.Create(FileName, fmCreate);
The fmCreate option means that if the file already exists, it will be replaced and overwritten by what we write.
The final step is to write the contents of the byte array to the file
if bytes<>nil then
stream.Write(bytes[0], Length(Bytes));
The if bytes<>nil check is to handle the case where the base64 string decodes to an empty array. If we were to remove that check then the following line would result in a runtime error if you were running with range checking enabled (which you should be doing). The call to stream.Write should be self-explanatory.

Answer 3

After looking into Soap.EncdDecd the one can find more platform independent way, as it's DecodeBase64 uses universal (no AnsiString) methods from System.NetEncoding.
Based on Uwe's sample:
uses
...
System.Classes,
System.NetEncoding;
...
procedure DecodeFile(const base64: String; const FileName: string);
var
stream: TBytesStream;
begin
stream := TBytesStream.Create(TNetEncoding.Base64.DecodeStringToBytes(base64));
try
stream.SaveToFile(Filename);
finally
stream.Free;
end;
end;

Answer 4

uses
Soap.EncdDecd;
function TForm1.EncodeFile(const FileName: string): AnsiString;
var
MemStream: TMemoryStream;
begin
MemStream := TMemoryStream.Create;
try
MemStream.LoadFromFile(Filename);
Result := EncodeBase64(MemStream.Memory, MemStream.Size);
finally
MemStream.Free;
end;
end;
function TForm1.DecodeFile(const base64: AnsiString): TBytesStream;
begin
Result := TBytesStream.Create(DecodeBase64(base64));
end;

Answer 5

I have a very old Delphi2006(v10.0.2558.35231 Update 2) and had to decode base64 UTF8 encoded input strings. I finally figured it out and heres an example for anyone interested.
Uses
IdCoderMIME; // Indy9
var
decoder: TIdDecoderMIME;
str: WideString;
- - -
decoder := TIdDecoderMIME.Create(nil);
str := base64DecodeUTF8(decoder, b64sourcestr);
decoder.Free;
- - -
function base64DecodeUTF8(decoder:TIdDecoderMIME; str:String): WideString;
var
stream:TMemoryStream;
utf8: UTF8String;
//idx:Integer;
begin
stream := TMemoryStream.Create;
try
decoder.DecodeToStream(str, stream);
setString(utf8, PChar(stream.Memory), stream.Size);
Result := UTF8Decode(utf8);
//for idx := 0 to stream.Size-1 do begin
// Writeln(PChar(stream.Memory)[idx] + ' ' + IntToStr(ORD(PChar(stream.Memory) [idx])) );
//end;
finally
stream.Free;
end;
end;