Regular Expressions 101

^start of line

Group 1(.*&)?

?repeats the group contents below at most once:

.*any character (except for line terminators), repeated any number of times

&the literal & (38₁₀ / 46₈ / 26₁₆)

date=the literal text date= (case sensitive)

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)

Non-Capturing Group(?:&(.*))?

?repeats the group contents below at most once:

&the literal & (38₁₀ / 46₈ / 26₁₆)

Group 2(.*)

.*any character (except for line terminators), repeated any number of times

$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

Detailed match information will be displayed here automatically.

25 tokens

Regular Expression

^(.*&)?date=[^&\n]*(?:&(.*))?$

New

date=15-sep-2022
date=15-sep-2022&foo=bar
arg=val&date=15-sep-2022&foo=bar
foo=bar&date=15-sep-2022&a=b

date=15-sep-2022
date=15-sep-2022&foo=bar
arg=val&date=15-sep-2022&foo=bar
foo=bar&date=15-sep-2022&a=b