Regular Expressions 101

^start of line

Non-Capturing Group(?:[01]\d?|2[0-3]?)

1st Alternative[01]\d?

Character Class[01]

0the literal 0 (48₁₀ / 60₈ / 30₁₆)

1the literal 1 (49₁₀ / 61₈ / 31₁₆)

\d?optionally matches a digit

2nd Alternative2[0-3]?

2the literal 2 (50₁₀ / 62₈ / 32₁₆)

Character Class[0-3]?

?matches at most one character from the set below:

0-3one character from 0 (48₁₀) to 3 (51₁₀)

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

?repeats the group contents below at most once:

:the literal : (58₁₀ / 72₈ / 3A₁₆)

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

?repeats the group contents below at most once:

Character Class[0-5]

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

\d?optionally matches a digit

$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

^(?:[01]\d?|2[0-3]?)(?::(?:[0-5]\d?)?)?$

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