regex101: Date Validation

1st Alternative^(?:(?:(?:0?[13578]|1[02])(\/|-|\.)31)\1|(?:(?:0?[1,3-9]|1[0-2])(\/?|-|\.)(?:29|30)\2))(?:(?:1[6-9]|[2-9]\d)?\d{2})$

^start of line

Non-Capturing Group(?:(?:(?:0?[13578]|1[02])(\/|-|\.)31)\1|(?:(?:0?[1,3-9]|1[0-2])(\/?|-|\.)(?:29|30)\2))

1st Alternative(?:(?:0?[13578]|1[02])(\/|-|\.)31)\1

Non-Capturing Group(?:(?:0?[13578]|1[02])(\/|-|\.)31)

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

1st Alternative0?[13578]

0?optionally matches the 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)

Group 1(\/|-|\.)

1st Alternative\/

\/the literal / (47₁₀ / 57₈ / 2F₁₆)

2nd Alternative-

-the literal - (45₁₀ / 55₈ / 2D₁₆)

3rd Alternative\.

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

31the literal text 31

\1the text saved by group 1

2nd Alternative(?:(?:0?[1,3-9]|1[0-2])(\/?|-|\.)(?:29|30)\2)

Non-Capturing Group(?:(?:0?[1,3-9]|1[0-2])(\/?|-|\.)(?:29|30)\2)

Non-Capturing Group(?:0?[1,3-9]|1[0-2])

1st Alternative0?[1,3-9]

0?optionally matches the literal 0 (48₁₀ / 60₈ / 30₁₆)

Character Class[1,3-9]

1the literal 1 (49₁₀ / 61₈ / 31₁₆)

,the literal , (44₁₀ / 54₈ / 2C₁₆)

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)

Group 2(\/?|-|\.)

1st Alternative\/?

\/?optionally matches the literal / (47₁₀ / 57₈ / 2F₁₆)

2nd Alternative-

-the literal - (45₁₀ / 55₈ / 2D₁₆)

3rd Alternative\.

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

Non-Capturing Group(?:29|30)

1st Alternative29

2nd Alternative30

\2the text saved by group 2

Non-Capturing Group(?:(?:1[6-9]|[2-9]\d)?\d{2})

$end of line

2nd Alternative^(?:(?:0?2)(\/?|-|\.)(?:29)\3(?:(?:(?:1[6-9]|[2-9]\d)?(?:0[48]|[2468][048]|[13579][26])|(?:(?:16|[2468][048]|[3579][26])00))))$

3rd Alternative^(?:(?:0?[1-9])|(?:1[0-2]))(\/?|-|\.)(?:0?[1-9]|1\d|2[0-8])\4(?:(?:1[6-9]|[2-9]\d)?\d{2})$

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

^(?:(?:(?:0?[13578]|1[02])(\/|-|\.)31)\1|(?:(?:0?[1,3-9]|1[0-2])(\/?|-|\.)(?:29|30)\2))(?:(?:1[6-9]|[2-9]\d)?\d{2})$|^(?:(?:0?2)(\/?|-|\.)(?:29)\3(?:(?:(?:1[6-9]|[2-9]\d)?(?:0[48]|[2468][048]|[13579][26])|(?:(?:16|[2468][048]|[3579][26])00))))$|^(?:(?:0?[1-9])|(?:1[0-2]))(\/?|-|\.)(?:0?[1-9]|1\d|2[0-8])\4(?:(?:1[6-9]|[2-9]\d)?\d{2})$

New

Regular Expressions 101

Regular Expression

Substitution