Regular Expressions 101

Explanation

Pro

^start of line

123-the literal text 123-

Non-Capturing Group(?:a[a-z]*-(*SKIP)(*F)|\w+-)?

?repeats the group contents below at most once:

1st Alternativea[a-z]*-(*SKIP)(*F)

athe literal a (97₁₀ / 141₈ / 61₁₆) (case insensitive)

Character Class[a-z]*

*matches any number of characters from the set below:

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

-the literal - (45₁₀ / 55₈ / 2D₁₆)

(*SKIP)acts like (*PRUNE), but the next unanchored match attempt starts where (*SKIP) was reached instead of at the next subject character

(*F)forces the current match attempt to fail at this position

2nd Alternative\w+-

\w+any word character, repeated at least once

-the literal - (45₁₀ / 55₈ / 2D₁₆)

456the literal text 456

$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

i modifier: insensitive. Matches without distinguishing uppercase and lowercase letters

Detailed match information will be displayed here automatically.

25 tokens

^123-(?:a[a-z]*-(*SKIP)(*F)|\w+-)?456$

New

123-456
123-7-456
123-Apple-456
123-0-456
123-Alphabet-456
123-b-456

123-456
123-7-456
123-Apple-456
123-0-456
123-Alphabet-456
123-b-456