please help in this challenge

Question

// the question: Think about how to properly declare a variable and variable scope, then fix the following code so that it compiles. Be sure to not change the intent or intended behavior of the code.

// the code: using System; namespace Treehouse.CodeChallenges { class Program { static void Main() {

        String input;

        try
        {
            input = Console.ReadLine();

            if (input == "quit")
            {
                string output = "Goodbye.";
            }
            else
            {
                string output = "You entered " + input + ".";
            }

        }
        catch (Exception)
        {

            Console.WriteLine(output);
            throw;

        }


    }

}

}

// the Error: Program.cs(26,35): error CS0103: The name `output' does not exist in the current context Compilation failed: 1 error(s), 0 warnings

//please answer

Answer 1 · 2018-01-24T17:35:21Z

January 24, 2018 5:35pm

C# variables are scoped to the code block that they're declared in. What does this mean? It means that a variable can only be referenced (i.e. used) within the same code block that it's declared in. In C#, code blocks are defined using a set of curly braces {}.

Let's look at an example.

static void Main()
{
    int age = 18;

    if (age >= 18)
    {
        // This `message` variable is only available within the `if` statement's curly braces.
        string message = "You're old enough to vote!";
    }
    else
    {
        // This `message` variable is only available within the `else` statement's curly braces.
        // Also, since this `message` variable is declared within a different scope 
        // than the `if` statement's `message` variable it's a completely different variable, 
        // even though it shares the same name.
        string message = "You're too young to vote.";
    }

    // Attempting to reference the `message` variable here will cause a build error.
    Console.WriteLine(message);
}

What we really want is one message variable, not two. Furthermore, we want our message variable to accessible outside of the if/else statements. We can accomplish that by declaring the message variable outside of the if/else statements, like this.

static void Main()
{
    int age = 18;
    string message = "";

    if (age >= 18)
    {
        // Notice the lack of a data type in front of the `message` variable.
        // We're not declaring the `message` variable here, 
        // we're just assigning a value to the existing `message` variable.
        message = "You're old enough to vote!";
    }
    else
    {
        // Same as above. We're just assigning a value here to the `message` variable.
        message = "You're too young to vote.";
    }

    // And now this will work as expected as the `message` variable was declared 
    // in the same scope as this call to the `Console.WriteLine` method call.
    Console.WriteLine(message);
}

I hope this helps!

~James

Answer 2 · 2017-12-31T19:22:07Z

December 31, 2017 7:22pm

Variables only exist in the scope they are declared.

"Output" is currently declared in the if/else statements. That means the variable is destroyed at the next closing curly brackets. To avoid this, you need to declare your string variable in a scope that englobes both the if/else statements and the catch method.

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Ahmad Al-arn'uti

Ahmad Al-arn'uti

please help in this challenge

2 Answers

James Churchill

James Churchill

Samuel Savaria

Samuel Savaria