Question

I am trying to make a little game in C#.
The program asks the user for a any number.
The user then presses “GO” (button1) and the program checks whether the number is an even number or not. (x % 2 == 0)

I’m trying to get the program to show 4 checkboxes/radio buttons out of total of 8 depending on each case.
For example:

• If the number is an EVEN NUMBER: The program will show options 2,5,3,6.
• If the number is an ODD NUMBER: The program will show options 1,4,7,8.

(Options 1-8 were already included in the design.)

I need help with the if (x % 2 == 0) part. What do I write in it to make the checkboxes/radiobuttons appear or disappear?

By the way, is there a way to ask the user for a number without him having to click “GO”?
Like, use ENTER instead. If yes, what event is that?
Also, is there a way to limit the textbox to INT only?

I know it’s asking you to do the job, but I have tried, and I’m still a real beginner, therefore I think my way of learning is by actually experiencing it.

public partial class Form1 : Form
{
    int x;
    public Form1()
    {
        InitializeComponent();
    }

    private void button1_Click(object sender, EventArgs e)
    {
        x = int.Parse(textBox1.Text);
        if (x % 2 == 0)
        {
        }
    }
}

Answer 1

The Visible property of the CheckBox (inherited from Control) will aid you in making the needed controls visible when you wish them to be. Your if would look something like,

if (num % 2 == 0) 
{
    box1.Visible = false;
    box2.Visible = true;
    // ...
}
else
{
    box1.Visible = true;
    box2.Visible = false;
    // ...
}

However, this can be optimized a bit by using the condition to set the visibility of all the CheckBoxs at the same time instead of coding two conditionals – something like:

box1.Visible = !(num % 2 == 0);
box2.Visible = (num % 2 == 0);
// ...

As for on pressing enter, check the OnKeyDown event for you control, you can do this through the designer. Your event method would look like:

private void myControl_OnKeyDown(object sender, KeyEventArgs e)
{
    if (e.KeyCode == Keys.Enter)
    {
        // Handle enter key pressed here
    }
}

This should help you with your problems.

ADDITIONAL RESPONSE

List<CheckBox> boxes = new List<CheckBox>();
// Add all boxes and do other stuff, disable all

foreach (CheckBox box in boxes)
{
    box.Visible = false;
}