How does the ? make a quantifier lazy in regex

Question

I\'ve been looking into regex lately and figured that the ? operator makes the *,+, or ? lazy. My question is how does it

Answer 1

Imagine you have the following text:

BAAAAAAAAD

The following regexs will return:

/B(A+)/ => 'BAAAAAAAA'
/B(A+?)/ => 'BA'
/B(A*)/ => 'BAAAAAAAA'
/B(A*?)/ => 'B'

The addition of the "?" to the + and * operators make them "lazy" - i.e. they will match the absolute minimum required for the expression to be true. Whereas by default the * and + operators are "greedy" and try and match AS MUCH AS POSSIBLE for the expression to be true.

Remember + means "one or more" so the minimum will be "one if possible, more if absolutely necessary" whereas the maximum will be "all if possible, one if absolutely necessary".

And * means "zero or more" so the minimum will be "nothing if possible, more if absolutely necessary" whereas the maximum will be "all if possible, zero if absolutely necessary".