Regular Expressions 101

Pro

^start of line

Positive Lookahead(?=.*([a-zA-Z])[a-zA-Z]\1)

.*any character (except for line terminators), repeated any number of times

Group 1([a-zA-Z])

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-Z]

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

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

\1the text saved by group 1

Character Class[a-zA-Z .]+

+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)

the literal (32₁₀ / 40₈ / 20₁₆)

.the literal . (46₁₀ / 56₈ / 2E₁₆)

$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-Z])[a-zA-Z]\1)[a-zA-Z .]+$

New

goingforeyecheckup
nan means not a number.
do not match her
match here

goingforeyecheckup
nan means not a number.
do not match her
match here