I had an issue with Process.Start today. I was trying to call an executable that requires the user to confirm the action with a keystroke, in this case “y”.

As far as I am aware, there is no mechanism within the .NET framework to deal with this kind of thing, so I had to resort to the following syntax:

echo y| cacls path /E /T /P username:F

Unfortunately, the command “echo” is a pseudo command contained within the command shell.

To get around this, I had to use the following for the process.

Process runner = new Process();
runner.StartInfo.FileName = "cmd.exe";
runner.StartInfo.Arguments = "/C echo y| cacls path /E /T /P username:F";
runner.Start();

There is probably a more elegant way to do this, but that’s what I came up with in the time allowed.

This falls under the category of “I would have known about this if I was not self-taught, and it would have saved me so much time.”

In general, the methods I have written in the past have only been able to cope with a single return value. This is not a problem if you want, for example, to return a value from a DataSet, or a simple transform. However, there are occasions where you need to do multiple operations on a single set of data. An example might be statistical analysis on a set of integers – return the average, the sum, minimum and maximum values, etc.

I discovered the out keyword today, and it used as follows.

private void GetStatistics(int value1, int value2, out int sum, out int difference)
{
    sum = value1 + value2;
    if(value1 > value2) difference = value1 - value2;
    else difference = value2 - value1;
}

private void process_Click(object sender, System.EventArgs e)
{
    int sum;
    int diff;
    GetStatistics(34,82,out sum,out diff);
    label1.Text = "Sum :: " + sum.ToString();
    label2.Text = "Difference :: " + diff.ToString();
}

The out keyword specifies that the parameter is to be returned when the function completes. In this simple example, the result would be that label1 shows “Sum :: 116″, and label2 shows “Difference :: 48″. It is that easy.

You will notice that in this example, there is no return value (since it is a void function), but it can be amended to allow different method types.

private string GetStatistics(int value1, int value2, out int sum, out int difference)
{
    sum = value1 + value2;
    if(value1 > value2) difference = value1 - value2;
    else difference = value2 - value1;
    return "I have finished that for you, sir";
}

private void button1_Click(object sender, System.EventArgs e)
{
    int sum;
    int diff;
    MessageBox.Show(GetStatistics(34,82,out sum,out diff));
    label1.Text = "Sum ::
 " + sum.ToString();
    label2.Text = "Difference :: " + diff.ToString();
}

In this example, you can see that the out parameters do not have to even be the same type as the method. Here we return a string from the method, alongside the sum and difference integer values.

Powerful, I think.