Difference between r'^specific expression$' and r'specific expression' [duplicate]

This question already has an answer here:

My doubt is that I came across a regex which checks whether a password is strong or not. What is the impact of ^ and $ in this expression.

a = compile(r'^(?=.*?[A-Z])(?=.*?[a-z])(?=.*?[0-9])(?=.*?[#?!@$%^&*-]).{8,}$')


It has ^ and $ signs in it. But the below code works the same as above.

a = compile(r'(?=.*?[A-Z])(?=.*?[a-z])(?=.*?[0-9])(?=.*?[#?!@$%^&*-]).{8,}')


If so why are they been used in the above code. Or is there reason for its usage. Thanks in advance!

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

2 Answers
2

The ^ means “beginning of a line” and the $ means “end of a line”.
In your case, every match is a line so you don't have any problem.

^

$

$

^ is followed by the string or pattern by which the string will be started with and $ follows the string or pattern by which the string will be ended with. For your case your regex matched with the pattern of the string without regarding the starting or ending portion.

^

$

regex

re.DOTALL

re.MULTILINE