Validate string based on custom format

Question

I want to validate a string based on a custom format: ___.___ or ___,___, 3 numbers followed by a dot or comma followed by 3 numbers (e.g. 123.456 or 123,456).

Currently, I have following code:

string InputText = "123.456"
bool result, result1, result2;
int test, test2;
result = Int32.TryParse(InputText.Substring(0, 3), out test);
result1 = (InputText[3] == '.' || InputText[3] == ',') ? true : false;
result2 = Int32.TryParse(InputText.Substring(4, 3), out test2);

if (result == false || result1 == false || result2 == false)
{
    Console.WriteLine("Error! Wrong format.");
}

This works just fine, however, this seems rather inefficient and unnecessarily complex; is there an alternative to this?

have you tried \d{3}[.,]\d{3}

Braj
– Braj

2014-08-02 16:11:30 +00:00
Commented Aug 2, 2014 at 16:11 — Braj
– Braj, Commented Aug 2, 2014 at 16:11

hwnd · Accepted Answer · 2014-08-02 16:43:05Z

2

Is there an alternative to this? Yes you can use Regex.IsMatch to do this.

String s = "123.456";
if (!Regex.IsMatch(s, @"^\d{3}[.,]\d{3}$")) {
    Console.WriteLine("Error! Wrong format.");
}

Explanation:

^        # the beginning of the string
 \d{3}   #   digits (0-9) (3 times)
 [.,]    #   any character of: '.', ','
 \d{3}   #   digits (0-9) (3 times)
$        # before an optional \n, and the end of the string

answered Aug 2, 2014 at 16:43

hwnd

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Comments

Avinash Raj · Accepted Answer · 2014-08-02 16:11:27Z

1

Pattern to validate 3 numbers followed by a dot or comma followed by 3 numbers is,

^\d{3}[,.]\d{3}$

DEMO

answered Aug 2, 2014 at 16:11

Avinash Raj

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Comments

Federico Piazza · Accepted Answer · 2014-08-02 16:21:53Z

1

Aditional to Avinash answer if you want to capture the numbers matching the format you can use the following regex:

\b(\d{3}[.,]\d{3})\b

Working demo

enter image description here

answered Aug 2, 2014 at 16:21

Federico Piazza

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2 Comments

Avinash Raj Over a year ago

While validating a string, it's better to give start and end patterns. Is screen-shot necessary?

Federico Piazza Over a year ago

@AvinashRaj you are totally right, I missed the part of "I want to validate" though about if a string matches the regex

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