Tag 8: Calculator: Windows Forms, Delegates

Form1.cs

using System;
using System.Windows.Forms;

namespace Calculator
{
    public partial class Form1 : Form
    {
        public delegate double operate(double x, double y);
        private operate op;

        public Form1()
        {
            InitializeComponent();
            textBox1.Text = "0";
            textBox2.Text = "0";
            label1.Text = "0";
        }

        private double addieren(double x, double y)
        {
            return  x + y;
        }

        private double subtrahieren(double x, double y)
        {
            return x - y;
        }

        private double dividieren(double x, double y)
        {
            return y == 0 ? 0 : (x / y);
        }

        private double multiplizieren(double x, double y)
        {
            return x * y;
        }

        private void button1_Click(object sender, EventArgs e)
        {
            op = new operate(addieren);
            label2.Text = "+";
        }

        private void button2_Click(object sender, EventArgs e)
        {
            op = new operate(subtrahieren);
            label2.Text = "-";
        }

        private void label1_Click(object sender, EventArgs e)
        {
        }

        private void textBox3_TextChanged(object sender, EventArgs e)
        {
        }

        private void button3_Click(object sender, EventArgs e)
        {
            if (op != null)
                label1.Text = op(double.Parse(textBox1.Text), double.Parse(textBox2.Text)).ToString();
        }

        private void button4_Click(object sender, EventArgs e)
        {
            op = new operate(multiplizieren);
            label2.Text = "*";
        }

        private void button5_Click(object sender, EventArgs e)
        {
            op = new operate(dividieren);
            label2.Text = "/";
        }
    }
}