Regular Expressions 101

^start of line

Character Class[-−]?

?matches at most one character from the set below:

-the literal - (45₁₀ / 55₈ / 2D₁₆)

−the literal − (8722₁₀ / 21022₈ / 2212₁₆)

Comment:dash or minus

Non-Capturing Group(?: [1-9]\d{0,2} (?:,\d{3})* | 0 )

1st Alternative [1-9]\d{0,2} (?:,\d{3})*

Character Class[1-9]

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

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

Non-Capturing Group(?:,\d{3})*

*repeats the group contents below any number of times:

,the literal , (44₁₀ / 54₈ / 2C₁₆)

\d{3}a digit, repeated exactly 3 times

2nd Alternative 0

0 the literal text 0

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

x modifier: extended. Ignores unescaped whitespace and comments outside character classes

Detailed match information will be displayed here automatically.

Search reference

Regular Expression

^
[-−]?  #dash or minus
(?: [1-9]\d{0,2}
    (?:,\d{3})*
  | 0
)
(?:\.\d+)?
$

Test String
New

Valid
0
0.00
0.1
0.01
0.001
0.0001
0.00001
1.0
1
8
9
10
11
12
20
21
99
100
101
111
999
1,000
1,001
2,100
9,999
10,000
999,999
1,000,000
1,000,001

Invalid
00
0,1
0,001
0.0000 1
0,100
9999
,111
999,9999,999

Regular Expression

Test StringNew

Test String
New