Regular Expressions 101

Pro

^start of line

Group 1((?!\b((?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)(?:(?<!\.)\b|\.)){4}).)*

*repeats the group contents below any number of times:

Negative Lookahead(?!\b((?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)(?:(?<!\.)\b|\.)){4})

\ban ASCII word boundary

Group 2((?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)(?:(?<!\.)\b|\.)){4}

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

Non-Capturing Group(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)

1st Alternative25[0-5]

25the literal text 25

Character Class[0-5]

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

2nd Alternative2[0-4][0-9]

2the literal 2 (50₁₀ / 62₈ / 32₁₆)

Character Class[0-4]

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

Character Class[0-9]

0-9one character from 0 (48₁₀) to 9 (57₁₀)

3rd Alternative[01]?[0-9][0-9]?

Character Class[01]?

?matches at most one character from the set below:

0the literal 0 (48₁₀ / 60₈ / 30₁₆)

1the literal 1 (49₁₀ / 61₈ / 31₁₆)

Character Class[0-9]

0-9one character from 0 (48₁₀) to 9 (57₁₀)

Character Class[0-9]?

?matches at most one character from the set below:

0-9one character from 0 (48₁₀) to 9 (57₁₀)

Non-Capturing Group(?:(?<!\.)\b|\.)

1st Alternative(?<!\.)\b

Negative Lookbehind(?<!\.)

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

\ban ASCII word boundary

2nd Alternative\.

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

.any character (except for line terminators)

$end of line

Global pattern flags

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

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

Detailed match information will be displayed here automatically.

25 tokens

^((?!\b((?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)(?:(?<!\.)\b|\.)){4}).)*$

New

10.123.34.12


asdADSas 3242 .

10.123.34.12

10.123.34.12


asdADSas 3242 .

10.123.34.12