.net regex meaning of [^\\.]+

Question

I have a question about a regex. Given this part of a regex:

(.[^\\.]+)

The part [^\.]+ Does this mean get everything until the first dot? So with this text:

Hello my name is Martijn. I live in Holland.

I get 2 results: both sentences. But when I leave the + sign, I get 2 two characters: he, ll, o<space>, my, etc. Why is that?

Answer 1

Because a dot outside a character class (ie, not between []) means (almost) any character.

So, .[^\\.] means match (almost) any character followed by something which is not a dot nor a backslash (dots don't need to be escaped in a character class to mean just a dot, but backslashes do),

This, in your example, is h (any character) e (not a dot nor a backslash) and so on and so forth.

Whereas with a + (one or more of not a dot nor a backslash) you will match all characters which are not dots until a dot.

Answer 2

The regex means: any one character followed by more than zero characters that are not a backslash or a period.

Answer 3

Your regex .[^\\.]+ means:

1. Match any character
2. Match any character until you get slash or a dot ".". Note that [^\\.] means NOT slash or NOT dot, which means either a dot or a slash is not a match. It will keep on matching characters until it founds a dot or slash because of the "+" at the end. It is called a greedy quantifier because of that.

When you input (quotes not included): "Hello my name is Martijn. I live in Holland." The matches are:

1. Hello my name is Martijn
2. . I live in Holland

Note that the dot is not included in the first match since it stops at n in Martijn and the second match starts with the dot.

When you remove the +: (.[^\\.]) It just means:

1. Match any character
2. Match any character except a dot or a slash.