Save file with different extension

Hi,

I am a newbie and am opening some files, adding some lines, then saving the files. I can't figure out how to save each file I open with a new extension while keeping the filename the same.

Here is how I am opening the files:

DefaultFile='';
[FileName,PathName] = uigetfile('*.*','Select File to Plot',DefaultFile); %choose file to open.
%%%% **************** Read the File ************* 
        fid=fopen(fullfile(PathName,FileName));

To save the file do I use the following fopen and if so what do I put where the question marks are?

fileID = fopen(??????,'w');

Thanks

Answer 1

You have another fopen() to open an output file. Your question marks should be replaced by the full file name of your output file. You can use sprintf() (if needed) and fullfile() to create that output file name. Then use fprintf to write text to it. Then call fclose() to close the two files.

Not sure I completely understand but here is what I did.

1. I replaced the question marks with FileName

fileID = fopen(FileName,'w');

2. The file was saved but with the original name AND extension. How do I replace the original extension with a new one (say data.dat to data.txt)

Thanks.

I just tried this:

[pathstr, name, ext] = fileparts(FileName)

Which worked to separate the file name from the extension. Now, how do I print the file by concatenating the name with the extension?

This saves the file without the extension. How do I add a ".txt" extension?

fileID = fopen(name,'w');

Thanks.

you can use horzcat(name,newext) , where newext is the new extension u wanna give.. and then fileID = fopen(horzcat(name,newext),'w');

Thanks. Just before you answered I used:

fname = strcat(name, '.txt');
fileID = fopen(fname,'w');

Thanks everyone for their help.

I'd do

[folder, oldBaseName, oldExt] = fileparts(oldFileName);
newBaseName = sprintf('%s.txt',oldBaseName);
newFullFuleName = fullfile(folder, newBaseName);

Thanks. I used that and it makes it easier to identify original and new file names when looking at the code.

@AsYouWish: Please accept this answer, if it solves your problem. Thanks.