Does Console.Write ever fail?

.net, c#, console.writeline, visual-studio

Solution

Based on your comments, I think either your `firstEnumerable` or `secondEnumerable` objects are `null`. But since you did not post how you obtain these objects, I can't comment on why they are `null` or how to fix it.

It's okay for them to contain `null` entries, or even be fully empty, but they themselves cannot be `null` or it will throw an `ArgumentNullException` when you call `.ToArray()` on them. This corresponds with the "value cannot be null" exception message you're seeing.

The reason why it's not crashing and burning hard is because you are swallowing (and logging?) the exceptions within your iteration loop with a `try/catch` block that was not posted in your code sample.

I'm guessing your actual code is something like this:

foreach (Contact contact in Contact.LoadWithPredicate(getAll))
{
    try
    {
        ...

        object[] firstEnumerable = null;
        object[] secondEnumerable = null;

        //some logic gates here which under some circumstances do not 
        //assign a valid instance to firstEnumerable or secondEnumerable

        ...
        Console.WriteLine(i); //this prints every time

        //Turn the Enumerables into strings for printing
        string firstEnumAsString = String.Join(", ", firstEnumerable.ToArray()); //exception here
        string secondEnumAsString = String.Join(", ", secondEnumerable.ToArray()); //or exception here

        Console.WriteLine("Email: " + firstString+ ", correspondance: " + secondString+ ", PAM addresses: " + firstEnumAsString+ ", famousPeople: " + secondEnumAsString);
        ...
    }
    catch
    {
        //maybe some logging? maybe not?
    }
}

This will print out the `i` value each time. But when it attempts to create `firstEnumAsString` or `secondEnumAsString` it throws an exception and never hits your second `Console.WriteLine("Email: " + ...);` thus producing the output you're seeing. It's not that the `Console.WriteLine` is failing, it's that you're never calling it in the first place.

Problem

Original source