Regular Expressions 101

Explanation

Pro

Group 1((?<=\/|=)wall|photo|video)

1st Alternative(?<=\/|=)wall

Positive Lookbehind(?<=\/|=)

1st Alternative\/

\/the literal / (47₁₀ / 57₈ / 2F₁₆)

2nd Alternative=

=the literal = (61₁₀ / 75₈ / 3D₁₆)

wallthe literal text wall (case sensitive)

2nd Alternativephoto

photothe literal text photo (case sensitive)

3rd Alternativevideo

videothe literal text video (case sensitive)

Group 2(-?[0-9]*)

-?optionally matches the literal - (45₁₀ / 55₈ / 2D₁₆)

Character Class[0-9]*

*matches any number of characters from the set below:

0-9one character from 0 (48₁₀) to 9 (57₁₀)

_the literal _ (95₁₀ / 137₈ / 5F₁₆)

Group 3([0-9]*)

Character Class[0-9]*

*matches any number of characters from the set below:

0-9one character from 0 (48₁₀) to 9 (57₁₀)

Group 4(\?reply=)?

?repeats the group contents below at most once:

\?the literal ? (63₁₀ / 77₈ / 3F₁₆)

reply=the literal text reply= (case sensitive)

Group 5((?<=reply=)[0-9]*)?

?repeats the group contents below at most once:

Positive Lookbehind(?<=reply=)

reply=the literal text reply= (case sensitive)

Character Class[0-9]*

*matches any number of characters from the set below:

0-9one character from 0 (48₁₀) to 9 (57₁₀)

Global pattern flags

g modifier: global. Finds all matches instead of stopping after the first

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25 tokens

((?<=\/|=)wall|photo|video)(-?[0-9]*)_([0-9]*)(\?reply=)?((?<=reply=)[0-9]*)?

There are no unit tests.