NulltoString eq in C#

Question

I have this method to validate email addresses:

public static bool isEmail(string inputEmail)
{
    inputEmail = NulltoString(inputEmail);
    string strRegex = @"^([a-zA-Z0-9_\-\.]+)@((\[[0-9]{1,3}" +
                      @"\.[0-9]{1,3}\.[0-9]{1,3}\.)|(([a-zA-Z0-9\-]+\" +
                      @".)+))([a-zA-Z]{2,4}|[0-9]{1,3})(\]?)$";
    Regex re = new Regex(strRegex);
    if (re.IsMatch(inputEmail))
        return (true);
    else
        return (false);
}

But I get the error: The name 'NulltoString' does not exist in the current context.

Is there a string method that is equivalent to NulltoString()?

There is no such thing as NulltoString. What did you expect? — John Cromartie, May 18 '11 at 19:04
Your method is wrong. http://stackoverflow.com/questions/1903356/email-validation-regular-expression/1903368#1903368 — SLaks, May 18 '11 at 19:05
At the very least, you shouldn't parse the regex every time you call the method. — SLaks, May 18 '11 at 19:06
@SsRide360 - I think John was wondering why you would ask for an equivalent to something called `NulltoString` without explaining what `NulltoString` is or how you would expect it to behave if it did exist. — Joel Mueller, May 18 '11 at 21:40
Ahh. I just saw a method with `NulltoString` in it so I assumed that it was some really really old deprecated method. — Soatl, May 19 '11 at 13:38

score 7 · Accepted Answer · answered May 18 '11 at 19:04

7

The C# language already has a good feature for this, the null-coalescing operator:

inputEmail = inputEmail ?? string.Empty;

answered May 18 '11 at 19:04

Steven

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@Mimisbrunnr: I'm just here to help, learn and get score some points ;-) – Steven May 18 '11 at 19:10

score 2 · Answer 2 · answered May 18 '11 at 19:04

2

Try using the following:

inputEmail = inputEmail ?? String.Empty;

answered May 18 '11 at 19:04

Mr47

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score 0 · Answer 3 · answered May 18 '11 at 19:05

I suggest

 public static bool isEmail(string inputEmail)
{
    inputEmail = inputEmail?? string.Empty;
    string strRegex = @"^([a-zA-Z0-9_\-\.]+)@((\[[0-9]{1,3}" +
          @"\.[0-9]{1,3}\.[0-9]{1,3}\.)|(([a-zA-Z0-9\-]+\" +
          @".)+))([a-zA-Z]{2,4}|[0-9]{1,3})(\]?)$";
    Regex re = new Regex(strRegex);
    if (re.IsMatch(inputEmail))
        return (true);
    else
        return (false);
}

More efficient than that:

     if (null == inputEmail)
         return false;

score 0 · Answer 4 · answered May 18 '11 at 19:07

0

You could try

if(string.IsNullOrEmpty(inputEmail))
    //throw exception

answered May 18 '11 at 19:07

Xaisoft

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NulltoString eq in C#

4 Answers4