Regular Expressions 101

Explanation
Pro

^start of line

Negative Lookahead(?!0+)

0+the literal 0 (48₁₀ / 60₈ / 30₁₆) , repeated at least once

Non-Capturing Group(?:\d+(?:[.,]\d{0,2})?)?

?repeats the group contents below at most once:

\d+a digit, repeated at least once

Non-Capturing Group(?:[.,]\d{0,2})?

?repeats the group contents below at most once:

Character Class[.,]

.the literal . (46₁₀ / 56₈ / 2E₁₆)

,the literal , (44₁₀ / 54₈ / 2C₁₆)

\d{0,2}a digit, repeated between 0 and 2 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

^(?!0+)(?:\d+(?:[.,]\d{0,2})?)?$

New

It should accept:
1
11,00
100,88
100
11.00
100.88

Shouldn't accept:
0
-5
0,55
0.55