MATLAB: Need to remove punctuation from a string that was pulled from a cell array

Question

I have a text file, and I am grabbing each line and entering that line into a cell array named 'input'. I am then applying a regex to remove punctuation from each cell.

The following code works, just as a test:

    test = 'I''m testing to remove punctuation... Did it work?'
    punct = regexp(test, '[^.,''!?]');
    test = test(punct)

However, the code below is my actual code, and it does not work:

    punct = regexp(input, '[^.,''!?]');
    for i = (1:size(input))
        temp = char(input{i})
        input{i} = temp(punct)
    end

I receive the following error on the line 'input{i} = temp(punct)'

Function 'subsindex' is not defined for values of class 'cell'.

Temp appears to be a character array (string) no different than test from above. However, Matlab seems to think it is still a cell, despite using curly braces to index it from input AND using char() to convert it (just to be sure).

Why is temp not acting like a proper string? How can I get this to work?

Thank you for your help.

Answer 1

FIXED:

Instead of attempting to use a regex, I simply used

    input = erase(input, '!')
    input = erase(input, '?')
    ...

and so on...

It feels a little hacky, but it's the only way I could get it to work through the cells.