Regular Expressions 101

^start of line

Negative Lookahead(?!\.)

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

Group 1((^|\.)([1-9]?\d|1\d\d|2(5[0-5]|[0-4]\d))){4}

{4}repeats the group contents below exactly 4 times:

Group 2(^|\.)

1st Alternative^

^start of line

2nd Alternative\.

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

Group 3([1-9]?\d|1\d\d|2(5[0-5]|[0-4]\d))

1st Alternative[1-9]?\d

Character Class[1-9]?

?matches at most one character from the set below:

1-9one character from 1 (49₁₀) to 9 (57₁₀)

\da digit

2nd Alternative1\d\d

1the literal 1 (49₁₀ / 61₈ / 31₁₆)

\da digit

3rd Alternative2(5[0-5]|[0-4]\d)

2the literal 2 (50₁₀ / 62₈ / 32₁₆)

Group 4(5[0-5]|[0-4]\d)

1st Alternative5[0-5]

5the literal 5 (53₁₀ / 65₈ / 35₁₆)

Character Class[0-5]

0-5one character from 0 (48₁₀) to 5 (53₁₀)

2nd Alternative[0-4]\d

Character Class[0-4]

0-4one character from 0 (48₁₀) to 4 (52₁₀)

\da digit

$end of line

Global pattern flags

g modifier: global. Finds all matches instead of stopping after the first

m modifier: multiline. Causes ^ and $ to match the start and end of each line, not only the start and end of the string

Detailed match information will be displayed here automatically.

26 tokens

Regular Expression

^(?!\.)((^|\.)([1-9]?\d|1\d\d|2(5[0-5]|[0-4]\d))){4}$

New

115.42.150.37
192.168.0.1
110.234.52.124

01.01.01.01
1.1.1.01
123123123213
210.110
255
y.y.y.y
255.0.0.y
666.10.10.20
4444.11.11.11
33.3333.33.3
365.1.1.1
123.123.123.123.123
.123.123.123.123
123.123.123.123.
1.2.3.256
1.2.260.1
1.333.1.1