Regular Expressions 101

Pro

^start of line

Non-Capturing Group(?:[1-9]\d*|0(?!(?:\.0+)?$))?

?repeats the group contents below at most once:

1st Alternative[1-9]\d*

Character Class[1-9]

1-9one character from 1 (49₁₀) to 9 (57₁₀)

\d*a digit, repeated any number of times

2nd Alternative0(?!(?:\.0+)?$)

0the literal 0 (48₁₀ / 60₈ / 30₁₆)

Negative Lookahead(?!(?:\.0+)?$)

Non-Capturing Group(?:\.0+)?

?repeats the group contents below at most once:

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

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

$end of line

Non-Capturing Group(?:\.\d+)?

?repeats the group contents below at most once:

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

\d+a digit, repeated at least once

$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.

26 tokens

^(?:[1-9]\d*|0(?!(?:\.0+)?$))?(?:\.\d+)?$

New

yes
1.0
1.1
0.1
11
no
0.0
-0.0
0
-1.0
-1.1
-0.1
-11

yes
1.0
1.1
0.1
11
no
0.0
-0.0
0
-1.0
-1.1
-0.1
-11