Regular Expressions 101

Pro

^start of line

Non-Capturing Group(?:[1-4](?:\.\d+)?|5(?:\.0+)?)

1st Alternative[1-4](?:\.\d+)?

Character Class[1-4]

1-4one character from 1 (49₁₀) to 4 (52₁₀)

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 Alternative5(?:\.0+)?

5the literal 5 (53₁₀ / 65₈ / 35₁₆)

Non-Capturing Group(?:\.0+)?

?repeats the group contents below at most once:

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

0+the literal 0 (48₁₀ / 60₈ / 30₁₆) , 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

^(?:[1-4](?:\.\d+)?|5(?:\.0+)?)$

New

Do match (Expectation):

1
1.5
1.584
2
4.68756
5
Don't match (Expectation):

0
.5
0.99
01
05
5.1
6

Do match (Expectation):

1
1.5
1.584
2
4.68756
5
Don't match (Expectation):

0
.5
0.99
01
05
5.1
6