Regular Expressions 101

Pro

^start of line

Positive Lookahead(?=([1-5]).*\1)

Group 1([1-5])

Character Class[1-5]

1-5one character from 1 (49₁₀) to 5 (53₁₀)

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

\1the text saved by group 1

Positive Lookahead(?=.+(?!\1)([1-5]).*\2)

.+any character (except for line terminators), repeated at least once

Negative Lookahead(?!\1)

\1the text saved by group 1

Group 2([1-5])

Character Class[1-5]

1-5one character from 1 (49₁₀) to 5 (53₁₀)

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

\2the text saved by group 2

Non-Capturing Group(?:\1|\2){5}

{5}repeats the group contents below exactly 5 times:

1st Alternative\1

\1the text saved by group 1

2nd Alternative\2

\2the text saved by group 2

$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

^(?=([1-5]).*\1)(?=.+(?!\1)([1-5]).*\2)(?:\1|\2){5}$

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