Regular Expressions 101

Pro

^start of line

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

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

Character Class[1-9]

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

?repeats the group contents below at most once:

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

Character Class[0-9]*

*matches any number of characters from the set below:

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

Character Class[1-9]

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

2nd Alternative0\.[0-9]*[1-9]

0the literal 0 (48₁₀ / 60₈ / 30₁₆)

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

Character Class[0-9]*

*matches any number of characters from the set below:

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

Character Class[1-9]

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

Global pattern flags

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

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

Detailed match information will be displayed here automatically.

25 tokens

Regular Expression

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

GOOD:
.01
.1
0.01
0.1
1
10
10.1
10.11
105.1
999.99
88.00

BAD:
12345678.54
00564.5412
00.451
1.
,25
..25
0025
01
00,25
0
.0
0.001
999.001
e123.12
1000

Substitution

GOOD:
.01
.1
0.01
0.1
1
10
10.1
10.11
105.1
999.99
88.00

BAD:
12345678.54
00564.5412
00.451
1.
,25
..25
0025
01
00,25
0
.0
0.001
999.001
e123.12
1000