Stumped on calculator operations in C#

Question

I was making a calculator using Windows Forms Application and I'm currently stumped. Here's my application so far, it can only do addition, but any amount of numbers.

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace Calculator
{
public partial class Form1 : Form
{
    int num;
    int answer = 0;
    int i;


    public Form1()
    {
        InitializeComponent();
    }



    private void plusButton_Click(object sender, EventArgs e)
    {          
        answer += System.Convert.ToInt32(textBox1.Text);            
        ClearTextbox();
    }

    private void minusButton_Click(object sender, EventArgs e)
    {
        //answer -= System.Convert.ToInt32(textBox1.Text);
        //ClearTextbox();
    }

    private void Form1_Load(object sender, EventArgs e)
    {

    }

    private void divideButton_Click(object sender, EventArgs e)
    {

    }

    private void multiplyButton_Click(object sender, EventArgs e)
    {

    }

    private void textBox1_TextChanged(object sender, EventArgs e)
    {

    }

    private void button1_Click(object sender, EventArgs e)
    {
        num = 1;
        displayInt(num);
    }

    private void button2_Click(object sender, EventArgs e)
    {
        num = 2;
        displayInt(num);
    }

    private void button3_Click(object sender, EventArgs e)
    {
        num = 3;
        displayInt(num);
    }

    private void button4_Click(object sender, EventArgs e)
    {
        num = 4;
        displayInt(num);
    }

    private void button5_Click(object sender, EventArgs e)
    {
        num = 5;
        displayInt(num);
    }

    private void button6_Click(object sender, EventArgs e)
    {
        num = 6;
        displayInt(num);
    }

    private void button7_Click(object sender, EventArgs e)
    {
        num = 7;
        displayInt(num);
    }

    private void button8_Click(object sender, EventArgs e)
    {
        num = 8;
        displayInt(num);
    }

    private void button9_Click(object sender, EventArgs e)
    {
        num = 9;
        displayInt(num);
    }

    private void button0_Click(object sender, EventArgs e)
    {
        num = 0;
        displayInt(num);
    }

    private void resetButton_Click(object sender, EventArgs e)
    {
        ClearTextbox();
        num = 0;
        answer = 0;

    }

    public void displayInt(int num)
    {
        textBox1.Text = textBox1.Text + num.ToString();
    }

    public void ClearTextbox()
    {
        textBox1.Clear();
    }

    public void DisplayAnswer(int answer)
    {
        answer += System.Convert.ToInt32(textBox1.Text); //Answer = Answer + Textbox Stuff


        textBox1.Clear();
        textBox1.Text = answer.ToString();
    }

    private void equalsButton_Click(object sender, EventArgs e)
    {
        DisplayAnswer(answer);
        num = 0;
        answer = 0;
    }


}
}

I'm not sure if there's a way to wait until another number key is pressed, and then do x + y. I heard about event handlers, but it's quite a vague topic to me.

Here's a picture: http://img196.imageshack.us/img196/4127/12464e13e5154a949a9a457.png

*I want it to be able to do operations to more then 2 numbers.

Thanks!

Answer 1

You would need to have a "+"-button and a "="-button. Then your calculator has two number fields and two states:

1) Entering first number

2) Entering second number

You could have a variable saying which number is being entered.

int field = 1;

When pressing a digit button, this digit has to be appended to the corresponding field.

When pressing the "+"-button change the state to

field = 2;

Now the digits will be appended to the second field.

When you press the "="-button, convert the two numbers, which are still strings now, to int's, add them and output them to a result field. Set the state back to

field = 1;

Also a "clear"-button would clear the fields and set field = 1;

---

Note: As Paul Sasik says, your code is a bit messy. I would help, if you gave your buttons meaningful names like btnDigit1, btnDigit2, btnPlus, btnEquals, btnClear. When you double-click a button in the designer an event handler like btnPlus_Click will be created. This is clearer than button17_Click.

Answer 2

Your code is a bit messy and it's hard to figure out your intent. Help with this code will be long in coming. I suggest following this simple calculator tutorial. It explains the concepts and steps very nicely, including button events.