Regular Expressions 101

^start of line

-?optionally matches the literal - (45₁₀ / 55₈ / 2D₁₆)

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

1st Alternative(?=[1-9]|0(?!\d))\d+(?:\.\d+)?

Positive Lookahead(?=[1-9]|0(?!\d))

1st Alternative[1-9]

Character Class[1-9]

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

2nd Alternative0(?!\d)

0the literal 0 (48₁₀ / 60₈ / 30₁₆)

Negative Lookahead(?!\d)

\da digit

\d+a digit, repeated at least once

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

?repeats the group contents below at most once:

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

\d+a digit, repeated at least once

2nd Alternative\.\d+

\.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.

25 tokens

Regular Expression

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

New

0
1
-1
1.2
-1.2
.123
-.124
0.12
-0.112