Neednt have done vs didn’t need to do
- I needn’t have attended the meeting.
- I didn’t need to attend the meeting.
- Sentence 1 means that I attended the meeting while it wasn’t necessary. The thing is, I didn’t know that it was unnecessary to go to the meeting. Maybe I regret it.
- Sentence 2 indicates that I didn’t attend the meeting because I knew it was unnecessary.
Needn’t have done vs didn’t need to do
- We use needn’t + have + past participle to speak about things that were done but were not necessary.
- We use didn’t need to + infinitive to talk about things that were unnecessary that’s why they weren’t done.
Needn’t have done vs didn’t need to do examples
- I needn’t have taken my umbrella. It did not rain.
- “I needn’t have got up early. My colleague called me and said that the meeting was postponed.” My father said
- I needn’t have prepared all that food. They phoned to say they are not coming.
- My dad didn’t need to buy any fruit. We had some bananas and apples in the fridge.
- I didn’t need to visit a dentist because I felt better this morning.
- I didn’t need to go shopping, but I did just for fun.
Take a look at the difference between Stop doing sth and stop to do sth