Regular Expressions 101

^start of line

Group 1(((0)|([1-9]\d?)|(1\d\d)|(2[0-5]{2}))\.?){0,3}

{0,3}repeats the group contents below between 0 and 3 times:

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

1st Alternative(0)

Group 3(0)

0the literal 0 (48₁₀ / 60₈ / 30₁₆)

2nd Alternative([1-9]\d?)

Group 4([1-9]\d?)

Character Class[1-9]

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

\d?optionally matches a digit

3rd Alternative(1\d\d)

Group 5(1\d\d)

1the literal 1 (49₁₀ / 61₈ / 31₁₆)

\da digit

4th Alternative(2[0-5]{2})

Group 6(2[0-5]{2})

2the literal 2 (50₁₀ / 62₈ / 32₁₆)

Character Class[0-5]{2}

{2}matches exactly 2 characters from the set below:

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

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

Group 7((0)|([1-9]\d?)|(1\d\d)|(2[0-5]{2}))?

?repeats the group contents below at most once:

1st Alternative(0)

Group 8(0)

0the literal 0 (48₁₀ / 60₈ / 30₁₆)

2nd Alternative([1-9]\d?)

Group 9([1-9]\d?)

Character Class[1-9]

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

\d?optionally matches a digit

3rd Alternative(1\d\d)

Group 10(1\d\d)

1the literal 1 (49₁₀ / 61₈ / 31₁₆)

\da digit

4th Alternative(2[0-5]{2})

Group 11(2[0-5]{2})

2the literal 2 (50₁₀ / 62₈ / 32₁₆)

Character Class[0-5]{2}

{2}matches exactly 2 characters from the set below:

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

$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.

Search reference

Regular Expression

^(((0)|([1-9]\d?)|(1\d\d)|(2[0-5]{2}))\.?){0,3}((0)|([1-9]\d?)|(1\d\d)|(2[0-5]{2}))?$

Test String
New

255.255.255.255
192.168.0.1
0.0.0.0
192.168.0.
192.168.0
192.1
0
33.33.33.33
2.2.99

255.255.255.255.
192.168.0.270
0.0.0.a
255.255.255. 255
192.168.0..
0.0.00.0

Regular Expression

Test StringNew

SubstitutionProcessing...

Test String
New

Substitution
Processing...