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 WindowsFormsApplication2
{
    public partial class Form1 : Form
    {
        private int c = 0;
        private string f,g;
        public Form1()
        {
            InitializeComponent();
        }
        private void button_text(string a)
        {
            if (c == 1)
            {
                textBox1.Text = a;

            }
            else {
                textBox1.Text = textBox1.Text + a;

            }

        }
        private void button1_Click(object sender, EventArgs e)
        {
            c++;
            button_text("1");
        }

        private void textBox1_TextChanged(object sender, EventArgs e)
        {

        }

        private void button2_Click(object sender, EventArgs e)
        {
            c++;
            button_text("2");
        }

        private void button3_Click(object sender, EventArgs e)
        {
            c++;
            button_text("3");
        }

        private void button4_Click(object sender, EventArgs e)
        {
            c++;
            button_text("4");
        }

        private void button5_Click(object sender, EventArgs e)
        {
            c++;
            button_text("5");
        }

        private void button6_Click(object sender, EventArgs e)
        {
            c++;
            button_text("6");
        }

        private void button7_Click(object sender, EventArgs e)
        {
            c++;
            button_text("7");
        }

        private void button8_Click(object sender, EventArgs e)
        {
            c++;
            button_text("8");
        }

        private void button9_Click(object sender, EventArgs e)
        {
            c++;
            button_text("9");
        }

        private void button10_Click(object sender, EventArgs e)
        {
            c++;
            button_text("0");
        }

        private void button15_Click(object sender, EventArgs e)
        {
            c = 0;
            if (g == "+") {
                textBox1.Text = (Convert.ToInt32(f) + Convert.ToInt32(textBox1.Text)).ToString();

            }
            else if (g == "-") {

                textBox1.Text = (Convert.ToInt32(f) - Convert.ToInt32(textBox1.Text)).ToString();
            }
            else if (g == "*")
            {

                textBox1.Text = (Convert.ToInt32(f) * Convert.ToInt32(textBox1.Text)).ToString();
            }
            else if (g == "/")
            {

                textBox1.Text = (double.Parse(f)/double.Parse(textBox1.Text)).ToString();
            }
        }

        private void button11_Click(object sender, EventArgs e)
        {
            g = "+";
            c = 0;
            f = textBox1.Text;

        }

        private void button12_Click(object sender, EventArgs e)
        {
            g = "-";
            c = 0;
            f = textBox1.Text;
        }

        private void button13_Click(object sender, EventArgs e)
        {
            g = "*";
            c = 0;
            f = textBox1.Text;
        }

        private void button14_Click(object sender, EventArgs e)
        {
            g = "/";
            c = 0;
            f = textBox1.Text;
        }


    }
}