posted by rfvv .
1. If I didn't wear a school uniform, then I would be happy every day.
2. If I didn't wear a school uniform, I would be happy every day.
(Which one is correct? Are both OK? Which one is popular? What is the difference between the two sentences because of 'then'? Thank you.)
Both are OK and both are commonly used. Even if the word "then" is not there, it's implied -- because of "if."