Writing strings and bytes to a MemoryStream - delphi

Question

How to write 'Hello World' string, clrf, and some random 10 bytes to a memory stream in Delphi?

Answer 1

I would consider using a binary writer for this task. This is a higher level class that takes care of the details of getting data into the stream.
var
Stream: TMemoryStream;
Writer: TBinaryWriter;
Bytes: TBytes;
....
Stream := TMemoryStream.Create;
try
Writer := TBinaryWriter.Create(Stream);
try
Writer.Write(TEncoding.UTF8.GetBytes('Hello World'+sLineBreak));
//if you prefer, use a different encoding for your text
Bytes := GetRandomBytes(10);//I assume you can write this
Writer.Write(Bytes);
finally
Writer.Free;
end;
finally
Stream.Free;
end;
I expect that your real problem is more involved than this. The benefit of using the writer class is that you insulate yourself from the gory details of spewing data to the stream.

Answer 2

var
ms: TMemoryStream;
s: String;
b: array[0..9] of Byte;
i: Integer;
begin
ms := TMemoryStream.Create;
try
s := 'Hello World' + #13#10;
ms.Write(s[1], Length(s) * SizeOf(Char));
for i := 0 to 9 do
b[i] := Random(256);
ms.Write(b[0], 10);
// ms.SaveToFile('C:\temp\test.txt');
{
ms.Memory can be used for free access e.g.
// build an empty buffer 5 characters
s := '';
SetLength(s,5);
ms.Position := 5;
// the position after which we want to copy
i := Length('Hallo ')*SizeOf(Char);
// copy bytes to string
Move(TByteArray(ms.Memory^)[i],s[1],Length(s) * SizeOf(Char));
Showmessage(s); // Display's "World"
}
finally
ms.Free;
end;
end;