Regular Expressions 101

^start of line

Group 1(.{0,2}|.{4,}|[^f\n]..|.[^o\n].|..[^o\n])

1st Alternative.{0,2}

.{0,2}any character (except for line terminators), repeated between 0 and 2 times

2nd Alternative.{4,}

.{4,}any character (except for line terminators), repeated at least 4 times

3rd Alternative[^f\n]..

Negated Character Class[^f\n]

fthe literal f (102₁₀ / 146₈ / 66₁₆) (case sensitive)

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

.any character (except for line terminators)

4th Alternative.[^o\n].

.any character (except for line terminators)

Negated Character Class[^o\n]

othe literal o (111₁₀ / 157₈ / 6F₁₆) (case sensitive)

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

.any character (except for line terminators)

5th Alternative..[^o\n]

.any character (except for line terminators)

Negated Character Class[^o\n]

othe literal o (111₁₀ / 157₈ / 6F₁₆) (case sensitive)

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

$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

^(.{0,2}|.{4,}|[^f\n]..|.[^o\n].|..[^o\n])$

New

Not:
foo
But:

Text with foo hereee

foo Text      

More foo

foo               
   ^ whitespace ^
1

12

Match this line