How do you add a file extension when creating a file based on function input?

I want to be able to use an input for a function and create a text file based on the fid. The strjoin() function always inputs a space in between the fid and the '.txt'. This is what I have now, but I need a more optimal method.

function[...] = name(fid)

   textfile = strjoin({fid,'.txt'})

end

The output would then look like 'fid .txt'. I need to have the space removed. Is there any better function than using strjoin()?

Answer 1

[Star Strider]

I’m not certain what you want (because I don’t know what ‘fid’ is), but see if:

textfile = [fid,'.txt'];

does what you want.

Example:

fid = 'FileNamePrefix';
textfile = [fid,'.txt']

produces:

textfile =

FileNamePrefix.txt

[Domenick Avanzi]

Yes, this exactly what I needed. I feel silly for not just putting it into an array from the beginning. Thank you

[Star Strider]

My pleasure!

[Image Analyst]

An alternate way, useful for when the filenames are really complicated

textfile = sprintf('%s.txt', fid);

Note that fid is the variable name commonly given to the output of fopen() and not to the base file name string, so I recommend you choose a different name for the fid variable, like, how about baseFileName?