Regular Expressions 101

^start of line

Group 1(0\d|1\d|2[0-4])

1st Alternative0\d

0the literal 0 (48₁₀ / 60₈ / 30₁₆)

\da digit

2nd Alternative1\d

1the literal 1 (49₁₀ / 61₈ / 31₁₆)

\da digit

3rd Alternative2[0-4]

2the literal 2 (50₁₀ / 62₈ / 32₁₆)

Character Class[0-4]

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

:the literal : (58₁₀ / 72₈ / 3A₁₆)

Group 2(0\d|[1-5]\d)

1st Alternative0\d

0the literal 0 (48₁₀ / 60₈ / 30₁₆)

\da digit

2nd Alternative[1-5]\d

Character Class[1-5]

1-5one character from 1 (49₁₀) to 5 (53₁₀)

\da digit

Non-Capturing Group(?::(0\d|[1-5]\d))?

?repeats the group contents below at most once:

:the literal : (58₁₀ / 72₈ / 3A₁₆)

Group 3(0\d|[1-5]\d)

1st Alternative0\d

0the literal 0 (48₁₀ / 60₈ / 30₁₆)

\da digit

2nd Alternative[1-5]\d

Character Class[1-5]

1-5one character from 1 (49₁₀) to 5 (53₁₀)

\da digit

Non-Capturing Group(?:.(00\d|0[1-9]\d|[1-9]\d{2}))?

?repeats the group contents below at most once:

.any character (except for line terminators)

Group 4(00\d|0[1-9]\d|[1-9]\d{2})

1st Alternative00\d

00the literal text 00

\da digit

2nd Alternative0[1-9]\d

0the literal 0 (48₁₀ / 60₈ / 30₁₆)

Character Class[1-9]

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

\da digit

3rd Alternative[1-9]\d{2}

Character Class[1-9]

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

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

$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.

26 tokens

Regular Expression

^(0\d|1\d|2[0-4]):(0\d|[1-5]\d)(?::(0\d|[1-5]\d))?(?:.(00\d|0[1-9]\d|[1-9]\d{2}))?$

New

Format : [hours]:[minutes]:[seconds].[milliseconds]

21:21:21.123

21:21:21

21:21

Substitution

Format : [hours]:[minutes]:[seconds].[milliseconds]

21:21:21.123

21:21:21

21:21