Return Multiple Values from Function and Populating Variables (2) in the Caller

Question

I have a function in class A:

public int RecordSummary()
        {
            int result = 0;
            int recordsAffected = 0;

            SqlCommand cmd = new SqlCommand("spIATRecordSummary", conn);
            cmd.CommandType = CommandType.StoredProcedure;

            var returnParameter = cmd.Parameters.Add("@RETURN_VALUE", SqlDbType.Int);
            returnParameter.Direction = ParameterDirection.ReturnValue;

            try
            {
                conn.Open();
                recordsAffected = cmd.ExecuteNonQuery();
                result = Convert.ToInt32(returnParameter.Value);
            }
            catch (Exception e)
            {
                MessageBox.Show(e.Message.ToString());
            }
            finally
            {
                conn.Close();
            }
            -- I want to return these two: 
            return result;
            return recordsAffected;
        }

I want to get 2 values from this function and return it to two different variables.

From the other class how would I go about populating two variables?

Class B:

int RESULT = RecordSummary();
int RECORDS_AFFECTED = RecordSummary();

I've been reading on tuples and using the out parameter but I'm not sure how the caller will actually retrieve the data. Any help?

Out parameters can be harder to understand so the Microsoft recommendation for class library design is to avoid out parameters: http://msdn.microsoft.com/en-us/library/ms229053(v=vs.100) — Martin Liversage, Sep 03 '12 at 06:22

score 1 · Accepted Answer · answered Sep 03 '12 at 06:18

Here's how you could use an out parameter:

int GetRecordSummary(out int recordsAffected)
{
    // If necessary - basically this variable *must* be definitely
    // assigned by the time you return; your code currently just
    // catches exceptions thrown by the block that would assign
    // a value :(
    recordsAffected = -1;
    ...
    // Code as before
    ...
    return result;
}

Then call it with:

int recordsAffected;
int result = GetRecordSummary(out recordsAffected);

See the MSDN documentation on out for more details.

Alternatives:

Create your own type to encapsulate the two values, and return a value of that type

Return a Tuple<int, int> if you're using .NET 4 or higher:

... in the method ...
return Tuple.Of(result, recordsAffected);

... in the caller ...
var results = GetRecordSummary();
int result = results.Item1;
int recordsAffected = results.Item2;

Return Multiple Values from Function and Populating Variables (2) in the Caller

1 Answers1