Regular Expressions 101

^start of line

20the literal text 20

Non-Capturing Group(?:2[0-3]|[01]\d)

1st Alternative2[0-3]

2the literal 2 (50₁₀ / 62₈ / 32₁₆)

Character Class[0-3]

0-3one character from 0 (48₁₀) to 3 (51₁₀)

2nd Alternative[01]\d

Character Class[01]

0the literal 0 (48₁₀ / 60₈ / 30₁₆)

1the literal 1 (49₁₀ / 61₈ / 31₁₆)

\da digit

\d*a digit, repeated any number of times

$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

Detailed match information will be displayed here automatically.

Search reference

Regular Expression

^20(?:2[0-3]|[01]\d)\d*$

Test String
New

20110512192714
20794709157481
20121203175303
20794709157481
20210131201708
20211101050154
20220501022609
79776361952441

20211101050154
20220501022609

Regular Expression

Test StringNew

Test String
New