Regex for password must contain at least eight characters, at least one number and both lower and uppercase letters and special characters

Question

I want a regular expression to check that:

A password contains at least eight characters, including at least one number and includes both lower and uppercase letter

Answer 1

@ClasG has already suggested:

^(?=\S*[a-z])(?=\S*[A-Z])(?=\S*\d)(?=\S*[^\w\s])\S{8,}$

but it does not accept _(underscore) as a special character (eg. Aa12345_).

An improved one is:

^(?=\S*[a-z])(?=\S*[A-Z])(?=\S*\d)(?=\S*([^\w\s]|[_]))\S{8,}$