Regular Expressions 101

Explanation

Pro

\ban ASCII word boundary

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

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

Non-Capturing Group(?:\d{1,2}|1\d{2}|2(?:[0-4]\d|5[0-5]))

1st Alternative\d{1,2}

\d{1,2}a digit, repeated between 1 and 2 times

2nd Alternative1\d{2}

1the literal 1 (49₁₀ / 61₈ / 31₁₆)

\d{2}a digit, repeated exactly 2 times

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

2the literal 2 (50₁₀ / 62₈ / 32₁₆)

Non-Capturing Group(?:[0-4]\d|5[0-5])

1st Alternative[0-4]\d

Character Class[0-4]

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

\da digit

2nd Alternative5[0-5]

5the literal 5 (53₁₀ / 65₈ / 35₁₆)

Character Class[0-5]

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

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

Non-Capturing Group(?:\d{1,2}|1\d{2}|2(?:[0-4]\d|5[0-5]))

1st Alternative\d{1,2}

\d{1,2}a digit, repeated between 1 and 2 times

2nd Alternative1\d{2}

1the literal 1 (49₁₀ / 61₈ / 31₁₆)

\d{2}a digit, repeated exactly 2 times

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

2the literal 2 (50₁₀ / 62₈ / 32₁₆)

Non-Capturing Group(?:[0-4]\d|5[0-5])

1st Alternative[0-4]\d

Character Class[0-4]

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

\da digit

2nd Alternative5[0-5]

5the literal 5 (53₁₀ / 65₈ / 35₁₆)

Character Class[0-5]

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

\ban ASCII word boundary

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

Unit Test Summary

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Quick Reference

26 tokens

Regular Expression

\b(?:(?:\d{1,2}|1\d{2}|2(?:[0-4]\d|5[0-5]))\.){3}(?:\d{1,2}|1\d{2}|2(?:[0-4]\d|5[0-5]))\b

Unit Tests

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