Base64的解码？

[youfly]

为什么在Delphi6里提供Base64Encode函数而没有相关的解码函数。还是我没有找到，忘指教。

[爱编程的老五]

你可以用indy misc面板中的Idbase64Decoder控件来完成解码.

[shuyi]

const
//BaseTable
BaseTable:string='ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=';


......


function FindInTable(CSource:char):integer;
begin
result:=Pos(string(CSource),BaseTable)-1;
end;

function DecodeBase64(Source:string):string;
var
SrcLen,Times,i:integer;
x1,x2,x3,x4,xt:byte;
begin
result:='';
SrcLen:=Length(Source);
Times:=SrcLen div 4;
for i:=0 to Times-1 do
begin
x1:=FindInTable(Source[1+i*4]);
x2:=FindInTable(Source[2+i*4]);
x3:=FindInTable(Source[3+i*4]);
x4:=FindInTable(Source[4+i*4]);
x1:=x1 shl 2;
xt:=x2 shr 4;
x1:=x1 or xt;
x2:=x2 shl 4;
result:=result+chr(x1);
if x3= 64 then break;
xt:=x3 shr 2;
x2:=x2 or xt;
x3:=x3 shl 6;
result:=result+chr(x2);
if x4=64 then break;
x3:=x3 or x4;
result:=result+chr(x3);
end;
end;