文件大小格式化成K、M、G的形式（BCB，__int64 -->> AnsiString）

AnsiString __fastcall FileSizeText( const __int64 FileSize )
{
__int64 mark = 1;
int i = 0;
static float result;
while ( ( result = (float)(FileSize) / mark ) > 1024.0 )
{
mark <<= 10;
if ( ++i > 3 )
break;
}
switch ( i )
{
case 1:
return "Size: " + FormatFloat( "0.00", result ) + " K";
case 2:
return "Size: " + FormatFloat( "0.00", result ) + " M";
case 3:
return "Size: " + FormatFloat( "0.00", result ) + " G";
default:
return "Size: " + AnsiString( FileSize ) + " Bytes";
}
}