What are the practical reasons to use the "out" keyword

Question

I have written a utility function:

public static void SerializeErrorMessage(int ErrorCode, string ErrorMessage, out byte[] Buffer)
{
    object ErrorJson = new { ErrorCode, ErrorMessage };
    string Serialized = JsonConvert.SerializeObject(ErrorJson);     
    Buffer = Encoding.UTF8.GetBytes(Serialized);
}

I'm wondering why I should/shouldn't have written it like this instead:

public static byte[] SerializeErrorMessage(int ErrorCode, string ErrorMessage)
{
    object ErrorJson = new { ErrorCode, ErrorMessage };
    string Serialized = JsonConvert.SerializeObject(ErrorJson);     
    byte[] Buffer = Encoding.UTF8.GetBytes(Serialized);
    return Buffer;
}

Is it just a matter of personal preference? Is the first function more performant than the second function?

in that instance I would say it's preference. It's often used as a way to 'return' multiple values — musefan, Sep 27 '17 at 15:15
Think about `public static bool TrySerializeErrorMessage()` method instead to see a usage of `out` keyword ;). — shA.t, Sep 27 '17 at 15:15
See all the try parse methods [TryParse](https://msdn.microsoft.com/en-us/library/f02979c7(v=vs.110).aspx) — Lithium, Sep 27 '17 at 15:15

score 0 · Answer 1 · answered Sep 27 '17 at 15:18

The out keyword is used when more than one value from a function needs to be returned, without wrapping the values in an object.

e.g. Integer.TryParse, has both a return value (bool if parse was successful), and an out parameter that returns the value if the parsing was successful.

In your case, there is no difference

What are the practical reasons to use the "out" keyword

1 Answers1