Ignoring the line continuation (...) when reading a text file

Hello all! I have a text file with some structure inputs that I'm reading and evaluating in MATLAB directly using the eval function. The file content looks similar to this:

test = struct;

test.data = struct;

test.data.dummy = cell(1, 1);

test.data.dummy{1} = '1234';

test.data.name = cell(1, 1);

test.data.name{1} = ...

'THIS IS THE NAME'

and the code I'm using looks similar to this:

location = 'D:\Documents\test.txt';
FileID = fopen(location)
while ~feof(FileID)
    line=fgetl(FileID)
    eval(line)
end
fclose(FileID)

When it comes to the three dots (line continuation), of course the eval function doesn't understand it. How can I have the code wait and gets the value after those three dots?

Thanks

[Stephen23]

What is stopping you from just running the file?

Or at worst, copying part of the file to another file and running that?

[Mohamed AKI Ahmed]

I needed it to work in the way I asked since it's connected to another program. Wanted things to be autonomous

[Stephen23]

"I needed it to work in the way I asked since it's connected to another program. Wanted things to be autonomous"

Getting MATLAB to copy the file and run it would be a neater approach to your original task. Lets try it right now:

% create text file:
writelines(["x=...","pi;","disp(x)","disp('It worked!')"],'mytest.txt')
% copy file (note how MATLAB does this, user does not do anything):
copyfile('mytest.txt','myscript.m')
% run file (note how MATLAB does this, user does not do anything):
run('myscript')

    3.1416

It worked!

So far everything worked exactly as expected. It seems quite "autonomous" to me.

Answer 1

[Voss]

You can rename the txt file to an m-file and run it like any other MATLAB script. The name of the m-file cannot be test.m in this case, since "test" is the name of a variable it uses. Here I rename it to test_script.m:

movefile('test.txt','test_script.m') % rename to some .m file
test_script                          % run the script

test = struct with fields:
    data: [1×1 struct]

movefile('test_script.m','test.txt') % rename back

whos                                 % show the workspace

  Name        Size            Bytes  Class     Attributes

  ans         1x33               66  char                
  cmdout      1x33               66  char                
  test        1x1               752  struct              

test.data.name                       % verify that the multi-line command worked ok

ans = 1×1 cell array
    {'THIS IS THE NAME'}

Another option would be to read and eval() the entire file at once (instead of one line at a time):

clear   % clear the old stuff, for testing the second approach
whos    % verify the workspace is empty

location = 'test.txt';
FileID = fopen(location);        % open the file
lines = fread(FileID,'*char').'; % read the whole file into a character vector
fclose(FileID);                  % close the file
eval(lines);                     % eval the file's contents

test = struct with fields:
    data: [1×1 struct]

whos                             % show the workspace

  Name          Size             Bytes  Class     Attributes

  FileID        1x1                  8  double              
  ans           1x1                  8  double              
  lines         1x172              344  char                
  location      1x8                 16  char                
  test          1x1                752  struct              

test.data.name                   % verify that the multi-line command worked ok

ans = 1×1 cell array
    {'THIS IS THE NAME'}

[Mohamed AKI Ahmed]

Thank you Voss. Since I'm not in control of that text file, and I want things to be autonumous (not requiring the user to copy paste and run anything) I went with your second solution. Thanks again for your help!

[Voss]

You're welcome!

Note that the first solution also does not require the "user" to do anything. The renaming and running of the file is done programmatically. Of course, you'd have to take care that the m-file to rename to doesn't already exist.

In any case, glad it's working for you!

[Stephen23]

"not requiring the user to copy paste and run anything"

The user does not have to "copy paste and run anything", you can get MATLAB to do both of those things for you. Voss even showed you exactly how, in their working example.

Why do you think that the user must "copy paste and run anything", when Voss already showed that they don't?