Regular Expressions 101

Positive Lookbehind(?<=&|^)

1st Alternative&

&the literal & (38₁₀ / 46₈ / 26₁₆)

2nd Alternative^

^start of line

(?i)applies the following effective flags to the remainder of the pattern: gmi

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

keythe literal text key (case insensitive)

(?-i)applies the following effective flags to the remainder of the pattern: gm

i modifier: -insensitive. Case-sensitive match

=the literal = (61₁₀ / 75₈ / 3D₁₆)

Negated Character Class[^&\n]*

*matches any number of characters outside the set below:

&the literal & (38₁₀ / 46₈ / 26₁₆)

\na line-feed (newline) character (ASCII 10)

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.

Search reference

Regular Expression

(?<=&|^)(?i)key(?-i)=[^&\n]*

cool=13&nice=zz&key=value&polo=0
Key=value&cool=13&nice=zz&polo=0
cool=13&nice=zz&polo=0&key=value

cool=13&nice=zz&myKey=value&polo=0