regex101: Date and time capturer

^start of line

Positive Lookahead(?=^(?:(\d\d(?:[02468][048]|[13579][26]))-02-29|\d{4}-(?:0[13578]|1[02])-31|\d{4}-(?:0[13-9]|1[0-2])-30|\d{4}-(?:0[1-9]|1[0-2])-(?:0[1-9]|1\d|2[0-8])))

^start of line

Non-Capturing Group(?:(\d\d(?:[02468][048]|[13579][26]))-02-29|\d{4}-(?:0[13578]|1[02])-31|\d{4}-(?:0[13-9]|1[0-2])-30|\d{4}-(?:0[1-9]|1[0-2])-(?:0[1-9]|1\d|2[0-8]))

1st Alternative(\d\d(?:[02468][048]|[13579][26]))-02-29

Group 1(\d\d(?:[02468][048]|[13579][26]))

\da digit

Non-Capturing Group(?:[02468][048]|[13579][26])

1st Alternative[02468][048]

Character Class[02468]

0the literal 0 (48₁₀ / 60₈ / 30₁₆)

2the literal 2 (50₁₀ / 62₈ / 32₁₆)

4the literal 4 (52₁₀ / 64₈ / 34₁₆)

6the literal 6 (54₁₀ / 66₈ / 36₁₆)

8the literal 8 (56₁₀ / 70₈ / 38₁₆)

Character Class[048]

0the literal 0 (48₁₀ / 60₈ / 30₁₆)

4the literal 4 (52₁₀ / 64₈ / 34₁₆)

8the literal 8 (56₁₀ / 70₈ / 38₁₆)

2nd Alternative[13579][26]

Character Class[13579]

1the literal 1 (49₁₀ / 61₈ / 31₁₆)

3the literal 3 (51₁₀ / 63₈ / 33₁₆)

5the literal 5 (53₁₀ / 65₈ / 35₁₆)

7the literal 7 (55₁₀ / 67₈ / 37₁₆)

9the literal 9 (57₁₀ / 71₈ / 39₁₆)

Character Class[26]

2the literal 2 (50₁₀ / 62₈ / 32₁₆)

6the literal 6 (54₁₀ / 66₈ / 36₁₆)

-02-29the literal text -02-29

2nd Alternative\d{4}-(?:0[13578]|1[02])-31

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

-the literal - (45₁₀ / 55₈ / 2D₁₆)

Non-Capturing Group(?:0[13578]|1[02])

1st Alternative0[13578]

0the literal 0 (48₁₀ / 60₈ / 30₁₆)

Character Class[13578]

1the literal 1 (49₁₀ / 61₈ / 31₁₆)

3the literal 3 (51₁₀ / 63₈ / 33₁₆)

5the literal 5 (53₁₀ / 65₈ / 35₁₆)

7the literal 7 (55₁₀ / 67₈ / 37₁₆)

8the literal 8 (56₁₀ / 70₈ / 38₁₆)

2nd Alternative1[02]

1the literal 1 (49₁₀ / 61₈ / 31₁₆)

Character Class[02]

0the literal 0 (48₁₀ / 60₈ / 30₁₆)

2the literal 2 (50₁₀ / 62₈ / 32₁₆)

-31the literal text -31

3rd Alternative\d{4}-(?:0[13-9]|1[0-2])-30

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

-the literal - (45₁₀ / 55₈ / 2D₁₆)

Non-Capturing Group(?:0[13-9]|1[0-2])

1st Alternative0[13-9]

0the literal 0 (48₁₀ / 60₈ / 30₁₆)

Character Class[13-9]

1the literal 1 (49₁₀ / 61₈ / 31₁₆)

3-9one character from 3 (51₁₀) 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)

-30the literal text -30

4th Alternative\d{4}-(?:0[1-9]|1[0-2])-(?:0[1-9]|1\d|2[0-8])

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

-the literal - (45₁₀ / 55₈ / 2D₁₆)

Non-Capturing Group(?:0[1-9]|1[0-2])

1st Alternative0[1-9]

2nd Alternative1[0-2]

-the literal - (45₁₀ / 55₈ / 2D₁₆)

Non-Capturing Group(?:0[1-9]|1\d|2[0-8])

Group 2(\d{4})

-the literal - (45₁₀ / 55₈ / 2D₁₆)

Group 3(\d\d?)

-the literal - (45₁₀ / 55₈ / 2D₁₆)

Group 4(\d\d?)

Non-Capturing Group(?:\x20(\d{2}):(\d{2})(?::(\d{2})(.\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\d(?:[02468][048]|[13579][26]))-02-29|\d{4}-(?:0[13578]|1[02])-31|\d{4}-(?:0[13-9]|1[0-2])-30|\d{4}-(?:0[1-9]|1[0-2])-(?:0[1-9]|1\d|2[0-8])))(\d{4})-(\d\d?)-(\d\d?)(?:\x20(\d{2}):(\d{2})(?::(\d{2})(.\d+)?)?)?$

New

This captures the year, month and day of a date at the 2nd, 3rd and 4th groups.
Also captures leap years in day 29 of February in 1st capturing group.
2014-05-31
2016-02-29
2004-08-10 13:02
2002-02-08 19:35:00
1999-12-31 23:59:59.999
1996-02-29 23:59:59.9999
Regex used: ^(?=^(?:(\d\d(?:[02468][048]|[13579][26]))-02-29|\d{4}-(?:0[13578]|1[02])-31|\d{4}-(?:0[13-9]|1[0-2])-30|\d{4}-(?:0[1-9]|1[0-2])-(?:0[1-9]|1\d|2[0-8]))$)(\d{4})-(\d\d?)-(\d\d?)$

Regular Expressions 101

Regular Expression

Extraction