Regular Expressions 101

Pro

^start of line

Group 1([1-9]\d{0,3}|1\d{4}|20000)

1st Alternative[1-9]\d{0,3}

Character Class[1-9]

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

\d{0,3}a digit, repeated between 0 and 3 times

2nd Alternative1\d{4}

1the literal 1 (49₁₀ / 61₈ / 31₁₆)

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

3rd Alternative20000

20000the literal text 20000

$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.

25 tokens

^([1-9]\d{0,3}|1\d{4}|20000)$

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