How do I return string as well as IEnumerable<T> from same method in C#?

Question

I have one generic method which does some operations and want to return result as string or IEnumerable<T>

  public IEnumerable<T> MyResult(string input)
  {
      // do something return string based on some
      // case or return IEnumerable<T>
  }

How do I achieve this in one method, and how do I maintain return type?

Answer 1

First of all: A method can not have multiple return types.

Even though this is bad design you could (A) add an out parameter or (B) create a DTO containing the enumerable and string and return that.

(A):

public IEnumerable<T> MyResult(string input, out string output)
{
    // do something 
}

(B):

public MyDTO MyResult(string input)
{
    // do something 
}

and

public class MyDTO 
{
    public IEnumerable<T> resultAsEnumerable {get; set;}

    public string resultAsString {get; set;}    
}