Regular Expressions 101

^start of line

Group 1(\.5|((?:[1-9])|(?:[1-2][0-9])|(?:3[0-1]))(\.5)?|31.5)

1st Alternative\.5

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

5the literal 5 (53₁₀ / 65₈ / 35₁₆)

2nd Alternative((?:[1-9])|(?:[1-2][0-9])|(?:3[0-1]))(\.5)?

Group 2((?:[1-9])|(?:[1-2][0-9])|(?:3[0-1]))

1st Alternative(?:[1-9])

Non-Capturing Group(?:[1-9])

Character Class[1-9]

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

2nd Alternative(?:[1-2][0-9])

Non-Capturing Group(?:[1-2][0-9])

Character Class[1-2]

1-2one character from 1 (49₁₀) to 2 (50₁₀)

Character Class[0-9]

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

3rd Alternative(?:3[0-1])

Non-Capturing Group(?:3[0-1])

3the literal 3 (51₁₀ / 63₈ / 33₁₆)

Character Class[0-1]

0-1one character from 0 (48₁₀) to 1 (49₁₀)

Group 3(\.5)?

?repeats the group contents below at most once:

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

5the literal 5 (53₁₀ / 65₈ / 35₁₆)

3rd Alternative31.5

31the literal text 31

.any character (except for line terminators)

5the literal 5 (53₁₀ / 65₈ / 35₁₆)

$end of line

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

Detailed match information will be displayed here automatically.

Search reference

Regular Expression

^(\.5|((?:[1-9])|(?:[1-2][0-9])|(?:3[0-1]))(\.5)?|31.5)$

New

31