How do I return the first string variable that isn't null or emtpy

Question

If I have 5 String variables and between 0 and 5 of them are null or empty is there an easy/short way of returning the first one that is not null or empty? I am using .NET 3.5

Answer 1

    private static string FirstNonEmptyString(params string[] values)
    {
        return values.FirstOrDefault(x => !string.IsNullOrEmpty(x));
    }

Called like this:

        Console.WriteLine(FirstNonEmptyString(one, two, three, four, five) );

Answer 2

Define an extension method:

static string Or(this string value, string alternative) {
    return string.IsNullOrEmpty(value) ? alternative : value;
}

Now you can say the following:

string result = str1.Or(str2).Or(str3).Or(str4) …

Answer 3

var myString = new string[]{first, second, third, fouth, fifth}
      .FirstOrDefault(s => !string.IsNullOrEmpty(s)) ?? "";

//if myString == "", then none of the strings contained a value  

edit: removed Where(), placed predicate in FirstOrDefault(), thanks Yuriy

Answer 4

If your strings are in an IEnumerable you can use First or FirstOrDefault:

strings.First(s => !string.IsNullOrEmpty(s))

Answer 5

If you're using .NET 3.5 this is very easy with Linq.

string[] strings = new[] {"", "a", "b", ""};

string firstNotNullOrEmpty = 
    strings.Where(s => !String.IsNullOrEmpty(s)).FirstOrDefault();

Answer 6

var found = new[]{first, second, third, fourth, fifth}.FirstOrDefault(x =>!String.IsNullOrEmpty(x));

Answer 7

Yes.

string selected = null;
foreach(string currStr in strArray)
    if(String.IsNullOrEmpty(currStr)==false)
    {
        selected = currStr;
        break;
    }

No expression trees, no LINQ abuse, no obscure language features. Same runtime performance and a first year CS student can figure out what you're doing.