这个preg_match语法与“。+？”匹配的是什么

Question

I know perl style regular expresions fairly well, but today I found one that I do not understand:

preg_match('/^On.+?wrote:.+?$/i',$line); //reduced example

What does the .+? mean? I undarstand the .+ alone, I understand .? alone. But .+?? It seems a bug to me.

The line should match popular citation prefixes in the email body and it is much more complicated along with look behinds, but this is the only part i can't understand, and still the regexp seems to work correclty.

Answer 1

+ means one or more and is greedy. +? means the same, it just is not greedy like usual regex are.

Edit: I wanted to explain it a little further, but the comment of deceze already explains enough.^^