I noticed multiple times, when writing in Microsoft Word that the program suggests a correction, from either form to the other.
I can't seem to follow the logic.
When is it better to say did not, and when is it better to say didn't?
Feel free to add or suggest relevant tags, as I am unfamiliar with the word for this subject in English.
EDIT:
above: Word tries to tell me what to do
Best Answer
You can see in this screenshot (from my computer) that Microsoft Word lists contractions in its grammar settings under "Style":
This is because using contractions in formal writing is generally frowned upon, unless they are used for a very specific purpose (e.g. quoting someone). The reason why Microsoft Word may suggest correcting contractions is simply to make your writing more formal.
In terms of when you should use did not as opposed to didn't, I think it depends on the situation, and on your relationship with the intended audience. If you're writing a dissertation or a report to your boss, maybe use did not; if you're writing a text or email to your friend, I'm sure didn't would be just fine.