Regular Expressions 101

Explanation

Pro

^start of line

Non-Capturing Group(?:(?:2[0-4][0-9]|25[0-5]|1?[0-9]?[0-9])\.){3}

{3}repeats the group contents below exactly 3 times:

Non-Capturing Group(?:2[0-4][0-9]|25[0-5]|1?[0-9]?[0-9])

1st 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)

2nd Alternative25[0-5]

25the literal text 25

Character Class[0-5]

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

3rd Alternative1?[0-9]?[0-9]

1?optionally matches the literal 1 (49₁₀ / 61₈ / 31₁₆)

Character Class[0-9]?

?matches at most one character from the set below:

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

Character Class[0-9]

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

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

Non-Capturing Group(?:2[0-4][0-9]|25[0-5]|[0-1]?[0-9]?[0-9])

1st 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)

2nd Alternative25[0-5]

25the literal text 25

Character Class[0-5]

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

3rd Alternative[0-1]?[0-9]?[0-9]

Character Class[0-1]?

?matches at most one character from the set below:

0-1one character from 0 (48₁₀) to 1 (49₁₀)

Character Class[0-9]?

?matches at most one character from the set below:

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

Character Class[0-9]

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

$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

Match Information

Detailed match information will be displayed here automatically.

Quick Reference

25 tokens

Regular Expression

^(?:(?:2[0-4][0-9]|25[0-5]|1?[0-9]?[0-9])\.){3}(?:2[0-4][0-9]|25[0-5]|[0-1]?[0-9]?[0-9])$

172.16.254.1

(?>!000|00|0)

Extraction

172.16.254.1

(?>!000|00|0)