Regular Expressions 101

Negative Lookbehind(?<!\w)

\wany word character

Non-Capturing Group(?:http://www\.example\.com)?

?repeats the group contents below at most once:

http://wwwthe literal text http://www (case insensitive)

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

examplethe literal text example (case insensitive)

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

comthe literal text com (case insensitive)

/the literal / (47₁₀ / 57₈ / 2F₁₆)

Group 1(\S+?)

\S+?any non-whitespace character, repeated at least once

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

pdfthe literal text pdf (case insensitive)

\ban ASCII word boundary

Global pattern flags

i modifier: insensitive. Matches without distinguishing uppercase and lowercase letters

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

Detailed match information will be displayed here automatically.

Search reference

Regular Expression

(?<!\w)(?:http://www\.example\.com)?/(\S+?)\.pdf\b

New

some containing string http://www.example.com/subfolder/name.pdf or /subfolder/name.pdf

<a href="/pdf/subdir/name.pdf">clickhere</a><a href="/pdf/subdir/name.pdf">2nd PDF</a>

Substitution

/wp-content/uploads/old/$1.pdf