Regular Expressions 101

^start of line

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

1st Alternative1?[0-9]{1,2}

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

Character Class[0-9]{1,2}

{1,2}matches between 1 and 2 characters from the set below:

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

2nd 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)

3rd Alternative25[0-5]

25the literal text 25

Character Class[0-5]

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

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

New

000000000000000
00
01
99
255
256
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250
asdf1.1.dd1.dd1