Regular Expressions 101

Explanation
Pro

^start of line

Group 1(.*)

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

Group 2(-)

-the literal - (45₁₀ / 55₈ / 2D₁₆)

Group 3(\d{1})

\d{1}a digit, repeated exactly 1 time

Group 4(.[^.]+)

.any character (except for line terminators)

Negated Character Class[^.]+

+matches at least one character outside the set below:

.the literal . (46₁₀ / 56₈ / 2E₁₆)

$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

^(.*)(-)(\d{1})(.[^.]+)$

P123456_1_flying-elephant-100x70-1.pdf

P123456_1_flying-elephant-100x70-1.pdf