Deleting comments from .tex file? [duplicate]

Question

I'm new to LaTeX and I'm just starting to create my own little template. I'm putting comments everywhere to make it easier to remember what command does what.

I'd like to have a seperate file that does not contain those comments though. Is there any easy way I can delete all comments from a .tex file?

Thanks

Answer 1

I hope you won't mind this suggestion, but it seems to me that when you compile the LaTeX document you will see all of your text without the comments. If that is sufficient for what you want then why not just have the compiled .pdf document plus the source .tex file.

When you edit your .tex document do the comments appear in a different colour? Many (most?) editors will put your comments in a different colour that make it much easier to see which parts of the .tex file are comments and which parts are not. I can see that if your comments are in the same colour as your main text that would be really confusing.

[I would encourage you to keep the comments (even if you just make them smaller/shorter) as I find that comments help me keep track of what LaTeX is doing... .... -- for me it would be even more confusing not to have the comments..... sorry I guess this may not be the answer you want]

Answer 2

1/ What you want to do

You want to tell your IDE (i.e., the program you use to write .tex files) to:

1. look for all comments in you text,
2. delete them — i.e. replace them with an empty string.

2/ Explaining your IDE what is a comment

The issue is then "how can I tell my IDE what a comment is?". First, let's define what a comment is. A comment:

1. is a unknown number of successive characters
2. starts with %
3. but is not preceded with \ (otherwise, you would delete sentences in which you use the percentage symbol % — e.g., in "I should definitively get a 13% raise!" that is written as following in your code: I should definitively get a 13\% raise!).
4. ends at the end-of-line.

To tell this to your IDE, you can use regular expressions (regex). Explaining regex is out of topic here, but the "regex code" you are looking for is:

(?<!\\)%.*

_{Explanation on the regex:}

• _{.*: you are looking for an unknown number of any character (implied here: ending at the end of line).}
• _{%: that should arrive after a % character.}
• _{(?<!\\): but the % character should not (!) be preceded ((?< )) with a backslash (\\).}

3/ Proceed to the deletion

You then "just" need to search for the previous regular expression and replace every matching string with an empty one.

"Just", because it isn't that easy. Indeed, the previous expression uses negative lookbehind, which is an advance regex functionality that is not implemented in every editor. We'll then have a look at a workaround.

(If your IDE is regex-lookaround enabled, you probably don't need me to tell you how to do a search and replace.)

---

Prior potentially damaging your code, you can test if it works on this text sample:

% this is a full line comment
This line starts with normal text,% and ends with a comment.
This line is 100\% text, without any comment.

---

4/ Workaround if you use TeXworks, TeXstudio, Atom, or any other IDE that does not support regex lookaround.

Here is a solution that doesn't use regex lookaround. The idea is to:

1. "protect" \% occurrences in your text,
2. delete comments
3. revert \% back to normal.

Ready? Go:

4.1/ Protecting \%

The idea here is to temporarily replace \% with something that: 1/ won't be deleted by the next regex, 2/ can easily be re-converted into \% afterwards without causing any false positive errors. What you need to do is:

• search for: \% (do not use "regex search")
• replace with: [this is a protected percentage symbol and will be soon be reverted back to normal] (unless you already have exactly this sentence in your document, obviously).

4.2/ Deleting comments

Now that we are sure all % characters in our documents are start of comments, we can bluntly delete them all:

• search for: %.* (use "regex search" here)
• replace with: (nothing, i.e., leave text input void)

4.3/ Reverting percentage symbols back to normal

Now we can undo our step 4.1. For that:

• search for: [this is a protected percentage symbol and will be soon be reverted back to normal] (or any string you used in step 4.1. Do not use "regex search".)
• replace with: \%

Et voilà!

5/ How to do a (regex) search and replace in my IDE?

This depends on your IDE. You want to make sure that your "Search and replace" function accepts regular expression (and will not blindly look for (?<!\\)%.* in your text).

• TeXworks: Go in the Search/Replace menu (or Ctrl+R). To activate the regex-search, tick the "Regular expression" box.
  
  4.1/
  
  4.2/
  
  4.3/
  

• TeXstudio: Hit Ctrl+R. To activate regex-search, click on the little Reg button at the end of the "Find" line.
  
  4.2/
  

• atom: Hit Ctrl+F. To activate regex-search, click on the .* button.
  
  4.2/