Can someone explain with need \ char before dot at pattern

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1

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Username with 2-20 chars

^[a-zA-Z][a-zA-Z0-9-_\.]{1,20}$

- and _ chat is fine but with if not set \ before .? I try works both ways? Why use? \. or just .

Thanks!

2

In a character class (square brackets) any character except ^ , - , ] or \ is a literal.

Which is why it works both ways.