Regular Expressions 101

^start of line

Group 1([a-z])

Character Class[a-z]

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

Negative Lookahead(?!\1)

\1the text saved by group 1

Character Class[a-z]

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

\1the text saved by group 1

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

Regular Expression

^([a-z])(?!\1)[a-z]\1

New

e.g. match against the following expressions:

abaxyz
bzbaaadsfsdf
but not

aaaxyz
abcdefg
bbbaaasdf