C＃中的NulltoString eq

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() ?

Answer 1

C＃语言已经有了一个很好的功能， null-coalescing运算符 ：

inputEmail = inputEmail ?? string.Empty;

Answer 2

尝试使用以下内容：

inputEmail = inputEmail ?? String.Empty;

Answer 3

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;

Answer 4

You could try

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