CODEWITHSUNDEEP
c#regexvalidation
mskuratowski
mskuratowski

Reputation: 4124

Write a regex for number notations

I created this regular expression:

^$|^[1-9]+([\.,]\d{0,2})?$

It should accept:

1
11,00
100,88 (error)
100 (error)
11.00
100.88

Shouldn't accept:

0
-5
0,55
0.55

How can I fix it?

Upvotes: 1

Views: 120

Answers (3)

Rob
Rob

Reputation: 1492

From my reading of your question you want the string "(error)" to be a valid suffix. Is that right? If so:

^$|^[1-9]+[0-9]*([\.,]\d{0,2})?( \(error\))?$

Upvotes: 0

AGB
AGB

Reputation: 2226

So long as the first character is a digit between 1 and 9, subsequent characters can be any digit. However, your expression excludes subsequent 0's; you need to allow for there to be any number of digits so long as the first character is between 1 and 9:

^$|^[1-9]\d*([\.,]\d{0,2})?$

Pattern Explanation:

  • ^ the beginning of the string
  • [1-9] any digit except "0"
  • \d* any digit between 0 and unlimited times
  • ([\.,]\d{0,2})?
    • (optionally) either "." or "," followed by between zero and 2 digits
  • $ end of string

See this example for further explanation and unit tests.

Upvotes: 1

Wiktor Stribiżew
Wiktor Stribiżew

Reputation: 626853

You can enclose the whole pattern with an optional group and use a \d instead of the [1-9] and add a (?!0+) negative lookahead restriction to exclude matching values with leading zeros:

^(?!0+)(?:\d+(?:[.,]\d{0,2})?)?$
 ^^^^^^^^^                   ^^

See the regex demo

If you do not want to match 53.-like values, you need to replace {0,2} with {1,2}.

Pattern details:

  • ^ - start of string
  • (?!0+) - no zeros at the beginning
  • (?:\d+(?:[.,]\d{0,2})?)? - optional (one or zero) sequence of:
    • \d+ - 1 or more digits
    • (?:[.,]\d{0,2})? - optional (one or zero) sequence of:
      • [.,] - either a . or ,
      • \d{0,2} - two, one or zero digits
  • $ - end of string.

Upvotes: 2

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