calc2/Form1.cs

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 OdintsovCalc2
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }
        float a, b;
        int count;
        bool znak = true;

        private void button17_Click(object sender, EventArgs e)
        {
            textBox1.Text = textBox1.Text + 0;
        }
        private void button13_Click(object sender, EventArgs e)
        {
            textBox1.Text = textBox1.Text + 1;
        }
        private void button14_Click(object sender, EventArgs e)
        {
            textBox1.Text = textBox1.Text + 2;
        }

        private void button15_Click(object sender, EventArgs e)
        {
            textBox1.Text = textBox1.Text + 3;
        }

        private void button9_Click(object sender, EventArgs e)
        {
            textBox1.Text = textBox1.Text + 4;
        }

        private void button10_Click(object sender, EventArgs e)
        {
            textBox1.Text = textBox1.Text + 5;
        }

        private void button11_Click(object sender, EventArgs e)
        {
            textBox1.Text = textBox1.Text + 6;
        }

        private void button5_Click(object sender, EventArgs e)
        {
            textBox1.Text = textBox1.Text + 7;
        }

        private void button6_Click(object sender, EventArgs e)
        {
            textBox1.Text = textBox1.Text + 8;
        }

        private void button7_Click(object sender, EventArgs e)
        {
            textBox1.Text = textBox1.Text + 9;
        }
        private void button18_Click(object sender, EventArgs e)
        {
            textBox1.Text = textBox1.Text + ",";
        }
        private void button4_Click(object sender, EventArgs e)
        {
            try
            {
                a = float.Parse(textBox1.Text);
                textBox1.Clear();
                count = 1;
                label2.Text = a.ToString() + "+";
                znak = true;
            }
            catch
            {
                textBox1.Text = "Не верный ввод";
            };
        }
        private void button8_Click(object sender, EventArgs e)
        {
            try
            {
                a = float.Parse(textBox1.Text);
                textBox1.Clear();
                count = 2;
                label2.Text = a.ToString() + "-";
                znak = true;
            }
            catch
            {
                textBox1.Text = "Не верный ввод";
            };
        }
        private void button12_Click(object sender, EventArgs e)
        {
            try
            {
                a = float.Parse(textBox1.Text);
                textBox1.Clear();
                count = 3;
                label2.Text = a.ToString() + "*";
                znak = true;
            }
            catch
            {
                textBox1.Text = "Не верный ввод";
            };
        }
        private void button16_Click(object sender, EventArgs e)
        {
            try
            {
                a = float.Parse(textBox1.Text);
                textBox1.Clear();
                count = 4;
                label2.Text = a.ToString() + "/";
                znak = true;
            }
            catch
            {
                textBox1.Text = "Не верный ввод";
            };
        }
        private void button19_Click(object sender, EventArgs e)
        {
            try
            {
                calculate();
                label2.Text = "";
            }
            catch
            {
                textBox1.Text = "Не верный ввод";
            };

        }
        private void calculate()
        {
            try
            {
                switch (count)
                {
                    case 1:
                        b = a + float.Parse(textBox1.Text);
                        textBox1.Text = b.ToString();
                        break;
                    case 2:
                        b = a - float.Parse(textBox1.Text);
                        textBox1.Text = b.ToString();
                        break;
                    case 3:
                        b = a * float.Parse(textBox1.Text);
                        textBox1.Text = b.ToString();
                        break;
                    case 4:
                        b = a / float.Parse(textBox1.Text);
                        textBox1.Text = b.ToString();
                        break;

                    default:
                        break;
                };
            }
            catch
            {
                textBox1.Text = "Не верный ввод";
            };

        }
        private void button3_Click(object sender, EventArgs e)
        {
            try
            {
                textBox1.Text = "";
                label2.Text = "";
            }
            catch
            {
                textBox1.Text = "Не верный ввод";
            };
        }
        private void button2_Click(object sender, EventArgs e)
        {
            try
            {
                int lenght = textBox1.Text.Length - 1;
                string text = textBox1.Text;
                textBox1.Clear();
                for (int i = 0; i < lenght; i++)
                {
                    textBox1.Text = textBox1.Text + text[i];
                }
            }
            catch
            {
                textBox1.Text = "Не верный ввод";
            };
        }
        private void button1_Click(object sender, EventArgs e)
        {
            try
            {
                if (znak == true)
                {
                    textBox1.Text = "-" + textBox1.Text;
                    znak = false;
                }
                else if (znak == false)
                {
                    textBox1.Text = textBox1.Text.Replace("-", "");
                    znak = true;
                }
            }
            catch
            {
                textBox1.Text = "Не верный ввод";
            };
        }
    }
}