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

namespace Maytinhbotui
{
    public partial class Form1 : Form
    {
        private bool Kiemtra;
        private string PhepToan, LastValue;
        public Form1()
        {
            InitializeComponent();
        }

        private void label1_Click(object sender, EventArgs e)
        {

        }

        private void Form1_Load(object sender, EventArgs e)
        {

        }

        private void label3_Click(object sender, EventArgs e)
        {

        }

        private void xoa_Click(object sender, EventArgs e)
        {
            khungketqua.Clear();
        }

        private void button19_Click(object sender, EventArgs e)
        {
            if (Kiemtra) khungketqua.Clear();
            khungketqua.Text = khungketqua.Text + "1";
            Kiemtra = false;
        }

        private void button17_Click(object sender, EventArgs e)
        {
            if (Kiemtra) khungketqua.Clear();
            khungketqua.Text = khungketqua.Text + "2";
            Kiemtra = false;
        }

        private void button16_Click(object sender, EventArgs e)
        {
            if (Kiemtra) khungketqua.Clear();
            khungketqua.Text = khungketqua.Text + "3";
            Kiemtra = false;
        }

        private void button12_Click(object sender, EventArgs e)
        {
            if (Kiemtra) khungketqua.Clear();
            khungketqua.Text = khungketqua.Text + "4";
            Kiemtra = false;
        }

        private void button11_Click(object sender, EventArgs e)
        {
            if (Kiemtra) khungketqua.Clear();
            khungketqua.Text = khungketqua.Text + "5";
            Kiemtra = false;
        }

        private void button10_Click(object sender, EventArgs e)
        {
            if (Kiemtra) khungketqua.Clear();
            khungketqua.Text = khungketqua.Text + "6";
            Kiemtra = false;
        }

        private void button6_Click(object sender, EventArgs e)
        {
            if (Kiemtra) khungketqua.Clear();
            khungketqua.Text = khungketqua.Text + "7";
            Kiemtra = false;
        }

        private void button5_Click(object sender, EventArgs e)
        {
            if (Kiemtra) khungketqua.Clear();
            khungketqua.Text = khungketqua.Text + "8";
            Kiemtra = false;
        }

        private void button4_Click(object sender, EventArgs e)
        {
            if (Kiemtra) khungketqua.Clear();
            khungketqua.Text = khungketqua.Text + "9";
            Kiemtra = false;
        }

        private void button3_Click(object sender, EventArgs e)
        {
            LastValue = khungketqua.Text;
            Kiemtra = true;
            PhepToan = "+";
        }

        private void button9_Click(object sender, EventArgs e)
        {
            LastValue = khungketqua.Text;
            Kiemtra = true;
            PhepToan = "-";
        }

        private void button14_Click(object sender, EventArgs e)
        {
            LastValue = khungketqua.Text;
            Kiemtra = true;
            PhepToan = "*";
        }

        private void button21_Click(object sender, EventArgs e)
        {
            LastValue = khungketqua.Text;
            Kiemtra = true;
            PhepToan = "/";
        }

        private void button23_Click(object sender, EventArgs e)
        {
            double a, b;
            a = Convert.ToDouble(LastValue);
            b = Convert.ToDouble(khungketqua.Text);

            if (PhepToan == "+")
                khungketqua.Text = Convert.ToString(a + b);
            else if (PhepToan == "-")
                khungketqua.Text = Convert.ToString(a - b);
            else if (PhepToan == "*")
                khungketqua.Text = Convert.ToString(a * b);
            else if (PhepToan == "/")
                khungketqua.Text = Convert.ToString(a / b);
        }

        private void button25_Click(object sender, EventArgs e)
        {
            if (Kiemtra) khungketqua.Clear();
            khungketqua.Text = khungketqua.Text + "0";
            Kiemtra = false;
        }

    }
}