Regular Expressions 101

Pro

^start of line

Positive Lookahead(?=[a-zA-Z0-9]{7})

Character Class[a-zA-Z0-9]{7}

{7}matches exactly 7 characters from the set below:

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

A-Zone character from A (65₁₀) to Z (90₁₀) (case sensitive)

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

Character Class[a-zA-Z]

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

A-Zone character from A (65₁₀) to Z (90₁₀) (case sensitive)

Character Class[a-zA-Z0-9]+

+matches at least one character from the set below:

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

A-Zone character from A (65₁₀) to Z (90₁₀) (case sensitive)

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

Non-Capturing Group(?:-[a-zA-Z0-9]+)?

?repeats the group contents below at most once:

-the literal - (45₁₀ / 55₈ / 2D₁₆)

Character Class[a-zA-Z0-9]+

+matches at least one character from the set below:

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

A-Zone character from A (65₁₀) to Z (90₁₀) (case sensitive)

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

^(?=[a-zA-Z0-9]{7})[a-zA-Z][a-zA-Z0-9]+(?:-[a-zA-Z0-9]+)?$

testtest
test123
t123543
test12333333333333fgfADFADF

test-t
t
-
-test123
test123-
test--123
test test 2#$@

testtest
test123
t123543
test12333333333333fgfADFADF

test-t
t
-
-test123
test123-
test--123
test test 2#$@