Regular Expressions 101

Explanation

Pro

1st Alternative^[a-zA-Z0-9]*([-_,\.\$])(?:\1*[a-zA-Z0-9]*)*$

^start of line

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

*matches any number of 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)

Group 1([-_,\.\$])

Character Class[-_,\.\$]

\(the literal ( (40₁₀ / 50₈ / 28₁₆)

\)-_one character from ) (41₁₀) to _ (95₁₀)

,the literal , (44₁₀ / 54₈ / 2C₁₆)

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

\$the literal $ (36₁₀ / 44₈ / 24₁₆)

Non-Capturing Group(?:\1*[a-zA-Z0-9]*)*

*repeats the group contents below any number of times:

\1*the text saved by group 1, repeated any number of times

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

*matches any number of 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)

$end of line

2nd Alternative^[a-zA-Z0-9]+$

^start of line

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.

26 tokens

^[a-zA-Z0-9]*([\(\)-_,\.\$])(?:\1*[a-zA-Z0-9]*)*$|^[a-zA-Z0-9]+$

New

abc_def
abc-def
abc--def
abc_-def
abc-def-ghi$jkl-mno
abc-def-ghi-jkl-mno
--abc-def-
abc

abc_def
abc-def
abc--def
abc_-def
abc-def-ghi$jkl-mno
abc-def-ghi-jkl-mno
--abc-def-
abc