CODEWITHSUNDEEP
regex
Ray
Ray

Reputation: 4929

Regex range between 0 and 100 including two decimal

I'm trying to figure out a regex expression that does the following. Both conditions below must be true: 1) Between 0 and 100 inclusive 2) Can contain one or two decimals only but not obligatory.

It should not allow 100.01 or 100.1 100 is the maximum value, or 100.0 or 100.00

I tried ^(100(?:\.00)?|0(?:\.\d\d)?|\d?\d(?:\.\d\d)?)$ which helped me in this question but this does not accept 99.0 (one decimal). I'm probably very close.

Upvotes: 2

Views: 5324

Answers (1)

Wiktor Stribiżew
Wiktor Stribiżew

Reputation: 626845

You just need to make each second decimal digit optional:

^(?:100(?:\.00?)?|\d?\d(?:\.\d\d?)?)$
              ^                 ^

See the updated regex demo. The 0(?:\.\d\d)? alternative is covered by \d?\d(?:\.\d\d)? one (as per Sebastian's comment) and can thus be removed.

The ? quantifier matches one or zero occurrences of the subpattern it quantifies.

Pattern details:

  • ^ - start of string
  • (?: - start of an alternation group:
    • 100(?:\.00?)? - 100, 100.0 or 100.00 (the .00 is optional and the last 0 is optional, too)
    • \d?\d(?:\.\d\d?)? - an optional digit followed by an obligatory digit followed with an optional sequence of a dot, a digit and an optional digit.
  • ) - end of the alternation group
  • $ - end of string.

BONUS: If the number can have either . (dot) or , (comma) as a decimal separator, you can replace all \. patterns in the regex with [.,]:

^(?:100(?:[.,]00?)?|\d?\d(?:[.,]\d\d?)?)$

Upvotes: 3

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