How to pass an array and a single element to a multiple argument method?

Question

Example:

public void foo(params string[] s) { ... }

We can call this method with:

a) foo("test", "test2", "test3") // multiple single strings
b) foo(new string[]{"test", "test2", "test3"}) // string array

But it is not possible to call the method with:

c) foo("test", new string[]{"test", "test2", "test3"})

So when I have a single string and an array of strings, do I have to put them into one array first to call the method? Or is there a nice workaround to tell the method to consider the string array as single strings?

Answer 1

While you can solve this without using an extension method, I actually recommend using this extension method as I find it very useful whenever I have a single object but need an IEnumerable<T> that simply returns that single object.

Extension method:

public static class EnumerableYieldExtension
{
    public static IEnumerable<T> Yield<T>(this T item)
    {
        if (item == null)
            yield break;

        yield return item;
    }
}

The extension method is useful in many scenarios. In your case, you can now do this:

string[] someArray = new string[] {"test1", "test2", "test3"};
foo(someArray.Concat("test4".Yield()).ToArray());