正则表达式查询以验证货币字符串 C#？

Question

I am in no way a master of Regex which is why I am here I currently have this:

\s?[^0-9]?\s?[0-9,]+([\\.]{1})?[0-9]+\s?

Link to regex101

To explain my validation attempt I am trying to validate that a string matches the correct formatting structure.

I only want to match strings such as:

• £1.00
• £10.00
• £100.00
• £1000.00
• £10,000.00
• £100,000.00
• £1,234,546.00

Validation rules :

• String must include a '£' at the start.
• String should always have 2 digits following a decimal place.
• Following the '£' only digits between 0-9 should be accepted
• If the string length is greater than 6 (after £1000.00) then commas need to be entered at the appropriate points (IE £10,000.00 - £100,000.00 - £1,000,000.00 - £10,000,000.00 etc)

For example, strings that shouldn't be accepted:

• £1
• £10.000
• £1,00.00
• £1,000.00
• 10,000.00
• £100,000,00
• £1.234.546

Really hoping that one of you amazing people can help me out, if you need anymore info then please let me know!

Answer 1

What about this?

new Regex(@"£\d{1,3}(\,\d{3})*\.\d{2}\b");

Edit:

new Regex(@"£((\d{1,4})|(\d{2,3}(\,\d{3})+)|(\d(\,\d{3}){2,}))\.\d{2}\b");

https://regex101.com/r/zSRw2B/1

Answer 2

You can try the pattern below :

  ^£(?:[0-9]{1,4}|[0-9]{2,3},[0-9]{3}|[0-9]{1,3}(?:,[0-9]{3}){2,})\.[0-9]{2}$

When pences are mandatory - \.[0-9]{2} we have 3 options for pounds:

  [0-9]{1,4}                   for sums in range £0 .. £9999
  [0-9]{2,3},[0-9]{3}          for sums in range £10,000 .. £999,999
  [0-9]{1,3}(?:,[0-9]{3}){2,}  for huge sums     £1,000,000 ..

Demo:

  using System.Linq;
  using System.Text.RegularExpressions;

  ...

  Regex regex = new Regex(
    @"^£(?:[0-9]{1,4}|[0-9]{2,3},[0-9]{3}|[0-9]{1,3}(?:,[0-9]{3}){2,})\.[0-9]{2}$";

  string[] tests = new string[] {
    "£1.00",
    "£10.00",
    "£100.00",
    "£1000.00",
    "£10,000.00",
    "£100,000.00",
    "£1,234,546.00",

    "£1",
    "£10.000",
    "£1,00.00",
    "£1,000.00",
    "10,000.00",
    "£100,000,00",
    "£1.234.546",
  };

  string report = string.Join(Environment.NewLine, tests
    .Select(test => $"{test,15} : {(regex.IsMatch(test) ? "Match" : "Fail")}"));

  Console.Write(report);

Outcome:

          £1.00 : Match
         £10.00 : Match
        £100.00 : Match
       £1000.00 : Match
     £10,000.00 : Match
    £100,000.00 : Match
  £1,234,546.00 : Match
             £1 : Fail
        £10.000 : Fail
       £1,00.00 : Fail
      £1,000.00 : Fail
      10,000.00 : Fail
    £100,000,00 : Fail
     £1.234.546 : Fail