計算機

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 WindowsFormsApplication1
{
    public partial class Form1 : Form
    {
        int cal, temp, logic;
        Boolean a = false;
        public Form1()
        {
            InitializeComponent();
        }
        private void button1_Click(object sender, EventArgs e)
        {
            if (a == false)
            {
                textBox1.Text += 1;
            }
            else
            {
                textBox1.Text = "1";
                a = false;
            }
        }
        private void button2_Click(object sender, EventArgs e)
        {
            if (a == false)
            {
                textBox1.Text += 2;
            }
            else
            {
                textBox1.Text = "2";
                a = false;
            }
        }
        private void button3_Click(object sender, EventArgs e)
        {
            if (a == false)
            {
                textBox1.Text += 3;
            }
            else
            {
                textBox1.Text = "3";
                a = false;
            }
        }
        private void button4_Click(object sender, EventArgs e)
        {
            if (a == false)
            {
                textBox1.Text += 4;
            }
            else
            {
                textBox1.Text = "4";
                a = false;
            }
        }
        private void button5_Click(object sender, EventArgs e)
        {
            if (a == false)
            {
                textBox1.Text += 5;
            }
            else
            {
                textBox1.Text = "5";
                a = false;
            }
        }
        private void button6_Click(object sender, EventArgs e)
        {
            if (a == false)
            {
                textBox1.Text += 6;
            }
            else
            {
                textBox1.Text = "6";
                a = false;
            }
        }
        private void button7_Click(object sender, EventArgs e)
        {
            if (a == false)
            {
                textBox1.Text += 7;
            }
            else
            {
                textBox1.Text = "7";
                a = false;
            }
        }
        private void button8_Click(object sender, EventArgs e)
        {
            if (a == false)
            {
                textBox1.Text += 8;
            }
            else
            {
                textBox1.Text = "8";
                a = false;
            }
        }
        private void button9_Click(object sender, EventArgs e)
        {
            if (a == false)
            {
                textBox1.Text += 9;
            }
            else
            {
                textBox1.Text = "9";
                a = false;
            }
        }
        private void button10_Click(object sender, EventArgs e)
        {
            if (a == false)
            {
                textBox1.Text += 0;
            }
            else
            {
                textBox1.Text = "0";
                a = false;
            }
        }
        private void button11_Click(object sender, EventArgs e)
        {
            temp = int.Parse(textBox1.Text);
            logic = 1;
            a = true;
        }
        private void button12_Click(object sender, EventArgs e)
        {
            temp = int.Parse(textBox1.Text);
            logic = 2;
            a = true;
        }
        private void button13_Click(object sender, EventArgs e)
        {
            temp = int.Parse(textBox1.Text);
            logic = 3;
            a = true;
        }
        private void button14_Click(object sender, EventArgs e)
        {
            temp = int.Parse(textBox1.Text);
            logic = 4;
            a = true;
        }
        private void button15_Click(object sender, EventArgs e)
        {
            switch (logic)
            {
                case 1:
                    cal = temp + int.Parse(textBox1.Text);
                    textBox1.Text = cal.ToString();
                    break;
                case 2:
                    cal = temp - int.Parse(textBox1.Text);
                    textBox1.Text = cal.ToString();
                    break;
                case 3:
                    cal = temp * int.Parse(textBox1.Text);
                    textBox1.Text = cal.ToString();
                    break;
                case 4:
                    if (int.Parse(textBox1.Text) != 0)
                    {
                        cal = temp / int.Parse(textBox1.Text);
                        textBox1.Text = cal.ToString();
                    }
                    else
                    {
                        MessageBox.Show("除數不得為零!");
                    }
                    break;
            }
            a = true;
        }
    }
}