Regular Expressions 101

Explanation

Pro

^start of line

Non-Capturing Group(?:[0-9]{0,4}|[0-9]{6,})

1st Alternative[0-9]{0,4}

Character Class[0-9]{0,4}

{0,4}matches between 0 and 4 characters from the set below:

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

2nd Alternative[0-9]{6,}

Character Class[0-9]{6,}

{6,}matches at least 6 characters from the set below:

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

$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

^(?:[0-9]{0,4}|[0-9]{6,})$

New

1
12
123
1234
12345 <-- only one it should not match
123456
1234567

1
12
123
1234
12345 <-- only one it should not match
123456
1234567