Regular Expressions 101

& the literal text &

Atomic Group(?> (?<name>[a-zA-Z][a-zA-Z\d]++) | \# (?> (?<dec>\d++) | (?<hex>x[\da-fA-F]++) ) )

1st Alternative (?<name>[a-zA-Z][a-zA-Z\d]++)

Group name(?<name>[a-zA-Z][a-zA-Z\d]++)

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\d]++

++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)

\da digit

2nd Alternative \# (?> (?<dec>\d++) | (?<hex>x[\da-fA-F]++) )

\#the literal # (35₁₀ / 43₈ / 23₁₆)

Atomic Group(?> (?<dec>\d++) | (?<hex>x[\da-fA-F]++) )

1st Alternative (?<dec>\d++)

Group dec(?<dec>\d++)

\d++a digit, repeated at least once

2nd Alternative (?<hex>x[\da-fA-F]++)

Group hex(?<hex>x[\da-fA-F]++)

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

Character Class[\da-fA-F]++

++matches at least one character from the set below:

\da digit

a-fone character from a (97₁₀) to f (102₁₀) (case sensitive)

A-Fone character from A (65₁₀) to F (70₁₀) (case sensitive)

;the literal text ;

Global pattern flags

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

X modifier: eXtra. A \ followed by a letter with no special meaning causes an error

s modifier: single line. Allows a dot to match line terminators

x modifier: extended. Ignores unescaped whitespace and comments outside character classes

Detailed match information will be displayed here automatically.

Search reference

Regular Expression

&
(?>  (?<name>[a-zA-Z][a-zA-Z\d]++)
  |  \# (?>  (?<dec>\d++)
          |  (?<hex>x[\da-fA-F]++)
        )
)
;

Test String
New

http://foo.com/bar?foo=bar&region=US&register=lowpass&reg_test=fail&trademark=correct
&amp; &lt; &gt; &nbsp;
&there4; &frac34;
&lArr; &Uuml; &THORN;
&#9; &#12345;
&#x20; &#x02DC; &#xA9; &#x1D306; &#x2603;

Regular Expression

Test StringNew

SubstitutionProcessing...

Test String
New

Substitution
Processing...