regex101: Matches MM/DD/YYYY for the years 1800 through 2099

^start of string

Group 1(((0[1-9]|1[012])\/(?!00|29)([012]\d)|(0[13-9]|1[012])\/(29|30)|(0[13578]|1[02])\/31)\/(18|19|20)\d{2}|02\/29\/((18|19|20)(0[48]|[2468][048]|[13579][26])|2000))

1st Alternative((0[1-9]|1[012])\/(?!00|29)([012]\d)|(0[13-9]|1[012])\/(29|30)|(0[13578]|1[02])\/31)\/(18|19|20)\d{2}

Group 2((0[1-9]|1[012])\/(?!00|29)([012]\d)|(0[13-9]|1[012])\/(29|30)|(0[13578]|1[02])\/31)

1st Alternative(0[1-9]|1[012])\/(?!00|29)([012]\d)

Group 3(0[1-9]|1[012])

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[012]

1the literal 1 (49₁₀ / 61₈ / 31₁₆)

Character Class[012]

0the literal 0 (48₁₀ / 60₈ / 30₁₆)

1the literal 1 (49₁₀ / 61₈ / 31₁₆)

2the literal 2 (50₁₀ / 62₈ / 32₁₆)

\/the literal / (47₁₀ / 57₈ / 2F₁₆)

Negative Lookahead(?!00|29)

1st Alternative00

00the literal text 00

2nd Alternative29

29the literal text 29

Group 4([012]\d)

Character Class[012]

0the literal 0 (48₁₀ / 60₈ / 30₁₆)

1the literal 1 (49₁₀ / 61₈ / 31₁₆)

2the literal 2 (50₁₀ / 62₈ / 32₁₆)

\da digit

2nd Alternative(0[13-9]|1[012])\/(29|30)

Group 5(0[13-9]|1[012])

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[012]

1the literal 1 (49₁₀ / 61₈ / 31₁₆)

Character Class[012]

0the literal 0 (48₁₀ / 60₈ / 30₁₆)

1the literal 1 (49₁₀ / 61₈ / 31₁₆)

2the literal 2 (50₁₀ / 62₈ / 32₁₆)

\/the literal / (47₁₀ / 57₈ / 2F₁₆)

Group 6(29|30)

1st Alternative29

29the literal text 29

2nd Alternative30

30the literal text 30

3rd Alternative(0[13578]|1[02])\/31

Group 7(0[13578]|1[02])

1st Alternative0[13578]

2nd Alternative1[02]

\/the literal / (47₁₀ / 57₈ / 2F₁₆)

31the literal text 31

\/the literal / (47₁₀ / 57₈ / 2F₁₆)

Group 8(18|19|20)

\d{2}a digit, repeated exactly 2 times

2nd Alternative02\/29\/((18|19|20)(0[48]|[2468][048]|[13579][26])|2000)

$end of string, or before its final line terminator

Search reference

Regular Expression

^(((0[1-9]|1[012])\/(?!00|29)([012]\d)|(0[13-9]|1[012])\/(29|30)|(0[13578]|1[02])\/31)\/(18|19|20)\d{2}|02\/29\/((18|19|20)(0[48]|[2468][048]|[13579][26])|2000))$

Test String
New

08/16/2005

Regular Expression

Test StringNew

Test String
New