Regular Expressions 101

Pro

^start of line

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

Group 1((0(\.[0-9]+)?)|([1-9]+[0-9]*(\.[0-9]+)?))

1st Alternative(0(\.[0-9]+)?)

Group 2(0(\.[0-9]+)?)

0the literal 0 (48₁₀ / 60₈ / 30₁₆)

Group 3(\.[0-9]+)?

?repeats the group contents below at most once:

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

Character Class[0-9]+

+matches at least one character from the set below:

0-9one character from 0 (48₁₀) to 9 (57₁₀)

2nd Alternative([1-9]+[0-9]*(\.[0-9]+)?)

Group 4([1-9]+[0-9]*(\.[0-9]+)?)

Character Class[1-9]+

+matches at least one character from the set below:

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

Character Class[0-9]*

*matches any number of characters from the set below:

0-9one character from 0 (48₁₀) to 9 (57₁₀)

Group 5(\.[0-9]+)?

?repeats the group contents below at most once:

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

Character Class[0-9]+

+matches at least one character from the set below:

0-9one character from 0 (48₁₀) to 9 (57₁₀)

$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

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

New

0
1
12
123
0.1
1.12
12.0123
1.23
-1
-12
-0.1
-1.12
-12.0123
-01.23
01.23
3000001230120312030123011.2323
12.

--123
-2323-
23.23.23
34..34

0
1
12
123
0.1
1.12
12.0123
1.23
-1
-12
-0.1
-1.12
-12.0123
-01.23
01.23
3000001230120312030123011.2323
12.

--123
-2323-
23.23.23
34..34