Regular Expressions 101

Explanation

Pro

\ban ASCII word boundary

Group 1([a-z]{1}[0-9]{4}|[a-z]{2}[0-9]{3}|[a-z]{3}[0-9]{2}|[a-z]{4}[0-9]{1})

1st Alternative[a-z]{1}[0-9]{4}

Character Class[a-z]{1}

{1}matches one character from the set below:

a-zone character from a (97₁₀) to z (122₁₀) (case sensitive)

Character Class[0-9]{4}

{4}matches exactly 4 characters from the set below:

0-9one character from 0 (48₁₀) to 9 (57₁₀)

2nd Alternative[a-z]{2}[0-9]{3}

Character Class[a-z]{2}

{2}matches exactly 2 characters from the set below:

a-zone character from a (97₁₀) to z (122₁₀) (case sensitive)

Character Class[0-9]{3}

{3}matches exactly 3 characters from the set below:

0-9one character from 0 (48₁₀) to 9 (57₁₀)

3rd Alternative[a-z]{3}[0-9]{2}

Character Class[a-z]{3}

{3}matches exactly 3 characters from the set below:

a-zone character from a (97₁₀) to z (122₁₀) (case sensitive)

Character Class[0-9]{2}

{2}matches exactly 2 characters from the set below:

0-9one character from 0 (48₁₀) to 9 (57₁₀)

4th Alternative[a-z]{4}[0-9]{1}

Character Class[a-z]{4}

{4}matches exactly 4 characters from the set below:

a-zone character from a (97₁₀) to z (122₁₀) (case sensitive)

Character Class[0-9]{1}

{1}matches one character from the set below:

0-9one character from 0 (48₁₀) to 9 (57₁₀)

\ban ASCII word boundary

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

\b([a-z]{1}[0-9]{4}|[a-z]{2}[0-9]{3}|[a-z]{3}[0-9]{2}|[a-z]{4}[0-9]{1})\b

New

Positive matches: a1111, aa111, aaa11, aaaa1
Negative matches: a1a1a, aa11a, aa11, 1aaaa