Regular Expressions 101

Pro

^start of line

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

$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.

25 tokens

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

New

123.34.5.67

123.34.5.67