当前上下文中不存在（C＃）

Question

I have code here:

  public Form1()
    {
        InitializeComponent();
        Random random1 = new Random();
        int randy = random1.Next(0, 5);

    }

When I try to run it here:

 private void button1_Click(object sender, EventArgs e)
    {
         if (number < randy)
              {
                  label1.Text = "Try a higher number"; //tell user to guess

I get the error:

The name 'randy' does not exist in this current context

Is there somwhere else I can put the Random code? When I put it under

 public partial class Form1 : Form
{...

I get the error

 A field initialize cannot reference non-static field, method, or property

EDIT

I am using this program to count guess of the random number. I cannot put it under the Button1_Click or I will get a new number every time.

Answer 1

You can declare randy at class level and assign its value in form constructor:

    private int randy;
    public Form1()
    {
        InitializeComponent();
        Random random1 = new Random();
        randy = random1.Next(0, 5);

    }
    private void button1_Click(object sender, EventArgs e)
    {
        if (number < randy)
        {
            label1.Text = "Try a higher number"; //tell user to guess
        }
    }

Answer 2

As I mentioned in the comment, randy should be declared as a class level field and value should be assigned to it in the constructor of the form or in any other part of the code where required for that matter.

The Form1 class should look as following.

public partial class Form1 : Form
{
    private int randy;

    public Form1()
    {
        InitializeComponent();
        Random random1 = new Random();
        randy = random1.Next(0, 5);
    }

    private void button1_Click(object sender, EventArgs e)
    {
        if (number < randy)
        {
            //Your code
        }
    }
}

Answer 3

The variables random1 and randy are local variables declared inside the constructor for your form and so they do not exist outside of that function. You need to make them member fields of the Form1 class. You can do this by declaring them outside of the constructor and assigning values in the constructor or inline with the member declarations. If you assign values in line they will effectively occur at the end of the constructor at runtime.

public class Form1 : Form {
    public Form1() {
        random = new Random();
    }

    private Random random;

    private void ButtonClick(){
        int randy = random.Next(0, 5);
        //Get `number` somehow...

        if (number < randy) {
             //Do something...
        } 
    }
}

}

See this guide to scopes in C#: http://www.blackwasp.co.uk/CSharpVariableScopes.aspx

Answer 4

You need to make put the variables you want to use at the class level, so they can be accessed by all the methods in your class:

public partial class Form1 : Form
{
    private int numberToGuess;
    private List<int> guesses = new List<int>();
    private Random rnd = new Random();

Then, you can choose your first random number in the constructor or in the Form_Load event:

private void Form1_Load(object sender, EventArgs e)
{
    numberToGuess = rnd.Next(1, 101);
}

Then, in your button1_Click event you can access the numbers. In my case, I put the Random variable at the class level as well, so when they choose the correct number, I can pick a new one right away. I also added a List of their previous guesses because I wanted to play around with the "warmer/colder" idea:

private void button1_Click(object sender, EventArgs e)
{
    int guess;

    if (int.TryParse(textBox1.Text, out guess))
    {
        if (guess == numberToGuess)
        {
            MessageBox.Show($"Good job! You got it in {guesses.Count + 1} tries!");
            guesses.Clear();
            numberToGuess = rnd.Next(1, 101);
            MessageBox.Show("I've chosen a new number. Let's play again.");
        }
        else
        {
            var direction = guess > numberToGuess ? "lower" : "higher";
            var message = $"Sorry, that's not it - try a {direction} number.";

            if (guesses.Any())
            {
                // Tell them if they're getting warmer or colder by comparing 
                // how close this guess is to how close the last guess was
                var tempMsg = Math.Abs(guess - numberToGuess) <
                              Math.Abs(guesses.Last() - numberToGuess)
                    ? "Good - you're getting warmer!"
                    : "Oh, no - you're getting colder.";

                message += $"{Environment.NewLine}{tempMsg}";
            }

            MessageBox.Show(message);
            guesses.Add(guess);
        }
    }
    else
    {
        MessageBox.Show($"{textBox1.Text} is not a valid number - try again!");
    }
}