Formatting String in Razor with String.Format not working correctly

Question

I'm having an issue formatting a simple string in Razor, I've verified that the syntax is correct in regular C# code, but once I migrate it to my HTML page using Razor and String.Format doesn't seem to work. I'm trying to format a phone number string from ########## to (###)###-#### so my code for this is @{ string number = contact.ContactNumber; string formattedNumber = String.Format("({0}){1}-{2}", number.Substring(0, 3), number.Substring(3, 3), number.Substring(6, 4)); } @{ string number = contact.ContactNumber; string formattedNumber = String.Format("({0}){1}-{2}", number.Substring(0, 3), number.Substring(3, 3), number.Substring(6, 4)); }

I'm trying to verify if this is correct just by doing alert(@formattedNumber) but it doesn't appear to be working, the alert won't even appear. However if my code is simply

@{ string number = contact.ContactNumber; string formattedNumber = String.Format("{0}{1}{2}", number.Substring(0, 3), number.Substring(3, 3), number.Substring(6, 4)); }

Note that this one should just display the regular number, and the alert will work correctly and display ########## Any suggestions on why the (###)###-#### isn't working?

Answer 1

Your formatting is correct, it's just the way you output it on the alert .

When you use @formattedNumber in your View this is substituted for the value in that variable. Passing that string directly to a JavaScript alert will not work in the first instance because you won't end up with a valid string to alert . It will work in the second instance as you will be left with a valid number passed to the alert function.

Imagining an example where contact.ContactNumber is 0123456789 the first example will give JavaScript code of

alert((012)345-6789);

which is invalid.

The second example will work because it gives JavaScript code of

alert(0123456789);

which is valid (it will alert 123456789 in this example).

As HaukurHaf points out in the comments, you actually want to output the result as a string so you need single quotes around the output in your JavaScript:

alert('@formattedNumber'); //note the single quotes

This will mean in the first example you'll get an output of:

alert('(012)345-6789');

Answer 2

Check your console, my guess is you're getting a JS error causing the alert to fail. Here's your code with output along with an alternative way to do this with regexes.

var number = "1112223333";

//an alternative method using regexes
var regexFormat = Regex.Replace(number, @"^(\d{3})(\d{3})(\d{4})$", "($1)$2-$3");

//The methods you provided
string formattedNumber = String.Format("{0}{1}{2}", number.Substring(0, 3), number.Substring(3, 3), number.Substring(6, 4));
string formattedNumber1 = String.Format("({0}){1}-{2}", number.Substring(0, 3), number.Substring(3, 3), number.Substring(6, 4));

Here's the output from this:

     regexFormat = (111)222-3333
 formattedNumber = 1112223333
formattedNumber1 = (111)222-3333

regexFormat and formattedNumber1 should both provide you with what you need. I personally find the regex easier to read in this instance.

Answer 3

How are you printing out the number in your HTML? Doing the following works just fine for me:

    @{
        string number = "0712345678";
        string formattedNumber = String.Format("({0}){1}-{2}", number.Substring(0, 3), number.Substring(3, 3), number.Substring(6, 4));
    }

    <div>@formattedNumber</div>

I suspect your problem isn't with the formatting of the string (the way you have it is perfectly legit) but possibly with the way you're trying to display the string?