confusion about Ruby regular expression to match valid String

Question

Suppose I hvae a match pattern in Ruby regular expression:

VALID_ID = /^[-a-z0-9_.]+$/i

I think it matchs all strings that with characters -, _, 0-9, 'a-z', 'A-Z'. But, I feel confused about the last character . here. What does it mean? Can you provide some examples to explain it?

`.` is a character literal here.. To match a name like `arup11.rakshit`,`arup.rakshit` etc — Arup Rakshit, Mar 20 '14 at 08:07

score 2 · Answer 1 · answered Mar 20 '14 at 08:07

2

It matches the char ., the . inside [] is just the dot char, doesn't have a special meaning.

answered Mar 20 '14 at 08:07

xdazz

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score 1 · Accepted Answer · answered Mar 20 '14 at 08:08

If you use the dot(.) outside the [] then it means any character except \n. But if you place this dot(.) inside the [](also known as character-class), then it means only to match the dot(.)

For example:

/[.]/ will match with .

and /./ will match with any characters excepts \n

confusion about Ruby regular expression to match valid String

2 Answers2