Regular Expressions 101

Pro

(?xm)applies the following effective flags to the remainder of the pattern: gxm

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

m modifier: multiline. Causes ^ and $ to match the start and end of each line, not only the start and end of the string

Non-Capturing Group(?:\s|^)

1st Alternative\s

\sa Unicode whitespace character

2nd Alternative^

^start of line

Group 1([-+]?(?:\b\d+\.\d*|\.?\d+)(?:[eE][-+]?\d+)?)

Character Class[-+]?

?matches at most one character from the set below:

-the literal - (45₁₀ / 55₈ / 2D₁₆)

+the literal + (43₁₀ / 53₈ / 2B₁₆)

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

1st Alternative\b\d+\.\d*

\ba Unicode word boundary

\d+a Unicode decimal digit, repeated at least once

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

\d*a Unicode decimal digit, repeated any number of times

2nd Alternative\.?\d+

\.?optionally matches the literal . (46₁₀ / 56₈ / 2E₁₆)

\d+a Unicode decimal digit, repeated at least once

Non-Capturing Group(?:[eE][-+]?\d+)?

?repeats the group contents below at most once:

Character Class[eE]

ethe literal e (101₁₀ / 145₈ / 65₁₆) (case sensitive)

Ethe literal E (69₁₀ / 105₈ / 45₁₆) (case sensitive)

Character Class[-+]?

?matches at most one character from the set below:

-the literal - (45₁₀ / 55₈ / 2D₁₆)

+the literal + (43₁₀ / 53₈ / 2B₁₆)

\d+a Unicode decimal digit, repeated at least once

Positive Lookahead(?=\s|$)

1st Alternative\s

\sa Unicode whitespace character

2nd Alternative$

$end of line

Global pattern flags

g modifier: global. Finds all matches instead of stopping after the first

Detailed match information will be displayed here automatically.

25 tokens

Regular Expression

(?xm)
(?:\s|^)
([-+]?(?:\b\d+\.\d*|\.?\d+)(?:[eE][-+]?\d+)?)
(?=\s|$)

New

0.2 2.1 3.1 ab 3 c abc23
4534.34534345
.456456
1.
1e545
1.1e435ff
.1e232
1.e343
1231ggg
112E+12
4
5545ggg
dfgdf.5444
12312.1231
.1231
1231
1.wrr
1 34345 234 -121
177
-1e+ -1e+0 1e-1