regex101: Date validation

Explanation

Pro

^start of line

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

-the literal - (45₁₀ / 55₈ / 2D₁₆)

Group 1(((0[13578]|1[02])-(0[1-9]|[12]\d|3[0-1]))|(02-(0[1-9]|[12]\d))|((0[469]|11)-(0[1-9]|[12]\d|30)))

1st Alternative((0[13578]|1[02])-(0[1-9]|[12]\d|3[0-1]))

Group 2((0[13578]|1[02])-(0[1-9]|[12]\d|3[0-1]))

Group 3(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)

-the literal - (45₁₀ / 55₈ / 2D₁₆)

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

1st Alternative0[1-9]

0the literal 0 (48₁₀ / 60₈ / 30₁₆)

Character Class[1-9]

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

2nd Alternative[12]\d

Character Class[12]

1the literal 1 (49₁₀ / 61₈ / 31₁₆)

2the literal 2 (50₁₀ / 62₈ / 32₁₆)

\da digit

3rd Alternative3[0-1]

3the literal 3 (51₁₀ / 63₈ / 33₁₆)

Character Class[0-1]

0-1one character from 0 (48₁₀) to 1 (49₁₀)

2nd Alternative(02-(0[1-9]|[12]\d))

Group 5(02-(0[1-9]|[12]\d))

02-the literal text 02-

Group 6(0[1-9]|[12]\d)

1st Alternative0[1-9]

0the literal 0 (48₁₀ / 60₈ / 30₁₆)

Character Class[1-9]

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

2nd Alternative[12]\d

Character Class[12]

1the literal 1 (49₁₀ / 61₈ / 31₁₆)

2the literal 2 (50₁₀ / 62₈ / 32₁₆)

\da digit

3rd Alternative((0[469]|11)-(0[1-9]|[12]\d|30))

Group 7((0[469]|11)-(0[1-9]|[12]\d|30))

Group 8(0[469]|11)

1st Alternative0[469]

2nd Alternative11

-the literal - (45₁₀ / 55₈ / 2D₁₆)

Group 9(0[1-9]|[12]\d|30)

$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

Quick Reference

26 tokens

Regular Expression

^\d{4}-(((0[13578]|1[02])-(0[1-9]|[12]\d|3[0-1]))|(02-(0[1-9]|[12]\d))|((0[469]|11)-(0[1-9]|[12]\d|30)))$

652015-07-017987987
2051-54-45
2222-12-31
2015-07-01
2015-07-32
2015-06-31
2015-02-30
6542015-07-10654654
6542222-12-31654

^[0-9]{4}-(((0[13578]|(10|12))-(0[1-9]|[1-2][0-9]|3[0-1]))|(02-(0[1-9]|[1-2][0-9]))|((0[469]|11)-(0[1-9]|[1-2][0-9]|30)))$

Substitution

652015-07-017987987
2051-54-45
2222-12-31
2015-07-01
2015-07-32
2015-06-31
2015-02-30
6542015-07-10654654
6542222-12-31654

^[0-9]{4}-(((0[13578]|(10|12))-(0[1-9]|[1-2][0-9]|3[0-1]))|(02-(0[1-9]|[1-2][0-9]))|((0[469]|11)-(0[1-9]|[1-2][0-9]|30)))$