Regular Expressions 101

Explanation

Pro

^start of line

<tagthe literal text <tag (case sensitive)

+the literal (32₁₀ / 40₈ / 20₁₆) , repeated at least once

Group 1([abc])

Character Class[abc]

athe literal a (97₁₀ / 141₈ / 61₁₆) (case sensitive)

bthe literal b (98₁₀ / 142₈ / 62₁₆) (case sensitive)

cthe literal c (99₁₀ / 143₈ / 63₁₆) (case sensitive)

=“the literal text =“

Group 2([xyz])

Character Class[xyz]

xthe literal x (120₁₀ / 170₈ / 78₁₆) (case sensitive)

ythe literal y (121₁₀ / 171₈ / 79₁₆) (case sensitive)

zthe literal z (122₁₀ / 172₈ / 7A₁₆) (case sensitive)

“the literal “ (8220₁₀ / 20034₈ / 201C₁₆)

+the literal (32₁₀ / 40₈ / 20₁₆) , repeated at least once

Negative Lookahead(?!\1)

\1the text saved by group 1

Group 3([abc])

Character Class[abc]

athe literal a (97₁₀ / 141₈ / 61₁₆) (case sensitive)

bthe literal b (98₁₀ / 142₈ / 62₁₆) (case sensitive)

cthe literal c (99₁₀ / 143₈ / 63₁₆) (case sensitive)

=“the literal text =“

Negative Lookahead(?!\2)

\2the text saved by group 2

Group 4([xyz])

Character Class[xyz]

xthe literal x (120₁₀ / 170₈ / 78₁₆) (case sensitive)

ythe literal y (121₁₀ / 171₈ / 79₁₆) (case sensitive)

zthe literal z (122₁₀ / 172₈ / 7A₁₆) (case sensitive)

“the literal “ (8220₁₀ / 20034₈ / 201C₁₆)

+the literal (32₁₀ / 40₈ / 20₁₆) , repeated at least once

Negative Lookahead(?!\1|\3)

1st Alternative\1

\1the text saved by group 1

2nd Alternative\3

\3the text saved by group 3

Character Class[abc]

athe literal a (97₁₀ / 141₈ / 61₁₆) (case sensitive)

bthe literal b (98₁₀ / 142₈ / 62₁₆) (case sensitive)

cthe literal c (99₁₀ / 143₈ / 63₁₆) (case sensitive)

=“the literal text =“

Negative Lookahead(?!\2|\4)

1st Alternative\2

\2the text saved by group 2

2nd Alternative\4

\4the text saved by group 4

Character Class[xyz]

xthe literal x (120₁₀ / 170₈ / 78₁₆) (case sensitive)

ythe literal y (121₁₀ / 171₈ / 79₁₆) (case sensitive)

zthe literal z (122₁₀ / 172₈ / 7A₁₆) (case sensitive)

“the literal “ (8220₁₀ / 20034₈ / 201C₁₆)

\/the literal / (47₁₀ / 57₈ / 2F₁₆)

>the literal > (62₁₀ / 76₈ / 3E₁₆)

$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

Unit Test Summary

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Quick Reference

25 tokens

Regular Expression

^<tag +([abc])=“([xyz])“ +(?!\1)([abc])=“(?!\2)([xyz])“ +(?!\1|\3)[abc]=“(?!\2|\4)[xyz]“\/>$

Unit Tests

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