Regular Expressions 101

Pro

^start of line

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

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

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

1st Alternative(25[0-5])

Group 3(25[0-5])

25the literal text 25

Character Class[0-5]

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

2nd Alternative(2[0-4]?\d?)

Group 4(2[0-4]?\d?)

2the literal 2 (50₁₀ / 62₈ / 32₁₆)

Character Class[0-4]?

?matches at most one character from the set below:

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

\d?optionally matches a digit

3rd Alternative(1\d{1,2}?)

Group 5(1\d{1,2}?)

1the literal 1 (49₁₀ / 61₈ / 31₁₆)

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

4th Alternative([1-9]\d?)

Group 6([1-9]\d?)

Character Class[1-9]

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

\d?optionally matches a digit

5th Alternative([1-9])

Group 7([1-9])

Character Class[1-9]

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

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

Group 8((25[0-5])|(2[0-4]?\d?)|(1\d{1,2}?)|([1-9]\d?)|([1-9]))

1st Alternative(25[0-5])

Group 9(25[0-5])

25the literal text 25

Character Class[0-5]

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

2nd Alternative(2[0-4]?\d?)

Group 10(2[0-4]?\d?)

2the literal 2 (50₁₀ / 62₈ / 32₁₆)

Character Class[0-4]?

?matches at most one character from the set below:

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

\d?optionally matches a digit

3rd Alternative(1\d{1,2}?)

Group 11(1\d{1,2}?)

1the literal 1 (49₁₀ / 61₈ / 31₁₆)

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

4th Alternative([1-9]\d?)

5th Alternative([1-9])

$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

Regular Expression

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

111
000
256
333
222
267
1.1.1.1
255.255.255.255
000.000.000.000
0.0.0.0
100.28.28.1

Substitution

111
000
256
333
222
267
1.1.1.1
255.255.255.255
000.000.000.000
0.0.0.0
100.28.28.1