TEXTREAD File not found error

Hi,

I've been trying to create a loop that will read an arbitrary text file under certain circumstances, but send an error for further prompt if it is not the correct file name (and/or extension).

However, I have the loop running perfectly if the file is there and correctly inputted by the user, if not then it still runs the next bit of the loop (the thank you message) and I get this error:

Error using textread (line 165)
File not found.

Error in Assignment (line 13)
    EEGData = textread(Datafile);

My script is:

Datafile=input('Please enter filename with extension: ','s');
if exist ('eegdata.txt', 'file');
    disp(sprintf('Thank you, please wait a moment'));
    EEGData = textread(Datafile);
    else
    disp(sprintf('I''m sorry, this file does not exist, try again'))
end

Thanks!

Answer 1

[Stephen23]

if 2==exist(Datafile, 'file')

[Zara Roddis]

If I run this

Datafile=input('Please enter filename with extension: ','s');
if 2==exist(Datafile, 'file')
    disp(sprintf('Thank you, please wait a moment'));
    EEGData = textread(Datafile);
    else
    disp(sprintf('I''m sorry, this file does not exist, try again'));
end

then it sends the displayed error message and runs the rest of the script even if the file isn't correctly identified.

[Jan]

There is no need for an sprintf() here. But disp() is not useful also. Call error() instead.

[Stephen23]

As Jan Simon wrote, you will probably find error more useful:

if 2 == exist(Datafile, 'file')
    disp('Thank you, please wait a moment');
    EEGData = textread(Datafile);
else
    error('I''m sorry, this file does not exist, try again')
end

Or simplify the whole thing by removing the if entirely and calling assert:

assert(2==exist(Datafile,'file'),'This file does not exist, try again')
disp('Thank you, please wait a moment');
EEGData = textread(Datafile);

[Zara Roddis]

Ah that works brilliantly, thank you both

[Zara Roddis]

Is there a way of incorporating this into a loop so the script doesn't have to be reloaded each time the user inputs the wrong file?

[Stephen23]

Try something like this:

isf = false;
msg = 'enter filename with extension: ';
while ~isf
     fnm = input(msg,'s');
     isf = 2==exist(fnm,'file');
     msg = 'try another filename: ';
end
disp('Thank you, please wait a moment');
EEGData = textread(fnm);

Personally I find throwing an error a better choice.