regex101: ISO 8601 Datetime Validation

^start of line

Group 1(\d{4})

\d{4}a digit, repeated exactly 4 times

Group 2(-(0[1-9]|1[0-2])(-([12]\d|0[1-9]|3[01]))([T\s]((([01]\d|2[0-3])((:)[0-5]\d))([\:]\d+)?)?(:[0-5]\d([\.]\d+)?)?([zZ]|([\+-])([01]\d|2[0-3]):?([0-5]\d)?)?)?)

-the literal - (45₁₀ / 55₈ / 2D₁₆)

Group 3(0[1-9]|1[0-2])

1st Alternative0[1-9]

0the literal 0 (48₁₀ / 60₈ / 30₁₆)

Character Class[1-9]

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

2nd Alternative1[0-2]

1the literal 1 (49₁₀ / 61₈ / 31₁₆)

Character Class[0-2]

0-2one character from 0 (48₁₀) to 2 (50₁₀)

Group 4(-([12]\d|0[1-9]|3[01]))

-the literal - (45₁₀ / 55₈ / 2D₁₆)

Group 5([12]\d|0[1-9]|3[01])

1st Alternative[12]\d

Character Class[12]

1the literal 1 (49₁₀ / 61₈ / 31₁₆)

2the literal 2 (50₁₀ / 62₈ / 32₁₆)

\da digit

2nd Alternative0[1-9]

0the literal 0 (48₁₀ / 60₈ / 30₁₆)

Character Class[1-9]

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

3rd Alternative3[01]

3the literal 3 (51₁₀ / 63₈ / 33₁₆)

Character Class[01]

0the literal 0 (48₁₀ / 60₈ / 30₁₆)

1the literal 1 (49₁₀ / 61₈ / 31₁₆)

Group 6([T\s]((([01]\d|2[0-3])((:)[0-5]\d))([\:]\d+)?)?(:[0-5]\d([\.]\d+)?)?([zZ]|([\+-])([01]\d|2[0-3]):?([0-5]\d)?)?)?

?repeats the group contents below at most once:

Character Class[T\s]

Tthe literal T (84₁₀ / 124₈ / 54₁₆) (case sensitive)

\sany whitespace character

Group 7((([01]\d|2[0-3])((:)[0-5]\d))([\:]\d+)?)?

?repeats the group contents below at most once:

Group 8(([01]\d|2[0-3])((:)[0-5]\d))

Group 9([01]\d|2[0-3])

1st Alternative[01]\d

Character Class[01]

0the literal 0 (48₁₀ / 60₈ / 30₁₆)

1the literal 1 (49₁₀ / 61₈ / 31₁₆)

\da digit

2nd Alternative2[0-3]

2the literal 2 (50₁₀ / 62₈ / 32₁₆)

Character Class[0-3]

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

Group 10((:)[0-5]\d)

Group 11(:)

Character Class[0-5]

\da digit

Group 12([\:]\d+)?

Group 13(:[0-5]\d([\.]\d+)?)?

Group 15([zZ]|([\+-])([01]\d|2[0-3]):?([0-5]\d)?)?

$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

Search reference

Regular Expression

^(\d{4})(-(0[1-9]|1[0-2])(-([12]\d|0[1-9]|3[01]))([T\s]((([01]\d|2[0-3])((:)[0-5]\d))([\:]\d+)?)?(:[0-5]\d([\.]\d+)?)?([zZ]|([\+-])([01]\d|2[0-3]):?([0-5]\d)?)?)?)$

Unit Tests

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