Regular Expressions 101

Group 1((25[0-5]|(2[0-4]|1\d|[1-9]|)\d)\.?\b){4}

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

Group 2(25[0-5]|(2[0-4]|1\d|[1-9]|)\d)

1st Alternative25[0-5]

25the literal text 25

Character Class[0-5]

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

2nd Alternative(2[0-4]|1\d|[1-9]|)\d

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

1st Alternative2[0-4]

2the literal 2 (50₁₀ / 62₈ / 32₁₆)

Character Class[0-4]

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

2nd Alternative1\d

1the literal 1 (49₁₀ / 61₈ / 31₁₆)

\da digit

3rd Alternative[1-9]

Character Class[1-9]

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

4th Alternative — matches an empty string

\da digit

\.?optionally matches the literal . (46₁₀ / 56₈ / 2E₁₆)

\ban ASCII word boundary

Global pattern flags

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

Detailed match information will be displayed here automatically.

Search reference

Regular Expression

((25[0-5]|(2[0-4]|1\d|[1-9]|)\d)\.?\b){4}

192.168.1.1
127.0.0.1
256.548.0.1
255.255.255.0
192.168.123.11
0.1
123.4
19864.684.1
123.123.123
123.123.260.123
0.3.0.1
226.0.5.1
255.255.255.255