Regular Expressions 101

Group 1(0(?!0)|[1-2]|3(?=[0-1]))

1st Alternative0(?!0)

0the literal 0 (48₁₀ / 60₈ / 30₁₆)

Negative Lookahead(?!0)

0the literal 0 (48₁₀ / 60₈ / 30₁₆)

2nd Alternative[1-2]

Character Class[1-2]

1-2one character from 1 (49₁₀) to 2 (50₁₀)

3rd Alternative3(?=[0-1])

3the literal 3 (51₁₀ / 63₈ / 33₁₆)

Positive Lookahead(?=[0-1])

Character Class[0-1]

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

\da digit

\/the literal / (47₁₀ / 57₈ / 2F₁₆)

Group 2(0(?!0)|1(?=[0-2]))

1st Alternative0(?!0)

0the literal 0 (48₁₀ / 60₈ / 30₁₆)

Negative Lookahead(?!0)

0the literal 0 (48₁₀ / 60₈ / 30₁₆)

2nd Alternative1(?=[0-2])

1the literal 1 (49₁₀ / 61₈ / 31₁₆)

Positive Lookahead(?=[0-2])

Character Class[0-2]

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

\da digit

\/the literal / (47₁₀ / 57₈ / 2F₁₆)

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

Global pattern flags

g modifier: global. Finds all matches instead of stopping after the first

Detailed match information will be displayed here automatically.

Search reference

Regular Expression

(0(?!0)|[1-2]|3(?=[0-1]))\d\/(0(?!0)|1(?=[0-2]))\d\/\d{4}

New

     some matched dates (DD/MM/YYYY):     33/18/2005     31/01/2009

basic check for month/day boundaries:     33/02/2005     12/18/2007

NO check for month specific boundary:     31/22/2009