Question

For the life of me, I cannot concatenate two(/three) strings. These are some codes I have tried:

dir := 'C:\Users\' + Username + '\Downloads\done.txt'; //"Username" is the computer's current username.
//another example vvv
dir := 'C:\Users\' + Username;
dir := dir + '\Downloads\done.txt';
//last example vvv
dir := Concat('C:\Users\', Username, '\Downloads\done.txt');

All of the examples always return the same result:

C:\Users\-username-

Never:

C:\Users\-username-\Downloads\done.txt

What am I doing wrong here?

Answer 1

My guess is that your Username variable contains #0 at its end and you’re outputing that variable to a certain Windows API function. For instance the following code will result to this misbehavior:

procedure TForm1.Button1Click(Sender: TObject);
var
  Dir: string;
  Username: string;
begin
  Username := 'Username' + #0;
  Dir := Concat('C:\Users\', Username, '\Downloads\done.txt');
  ShowMessage(Dir);
end;

My suggestion is to check the value of your Username variable and remove the extra #0 at the end if there’s some.