calculator/Form1.cs

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

namespace calculator
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void label1_Click(object sender, EventArgs e)
        {

        }

        private void textBox1_TextChanged(object sender, EventArgs e)
        {

        }

        private void button19_Click(object sender, EventArgs e)
        {
            textBox1.Text += "9";
        }

        private void button1_Click(object sender, EventArgs e)
        {
            textBox1.Text += "%";
        }

        private void button2_Click_1(object sender, EventArgs e)
        {
            textBox1.Text += "";
        }

        private void button3_Click(object sender, EventArgs e)
        {
            textBox1.Text += "(";
        }

        private void button4_Click(object sender, EventArgs e)
        {
            textBox1.Text += ")";
        }

        private void button5_Click(object sender, EventArgs e)
        {
            textBox1.Text = "";
            textBox2.Text = "";
            textBox1.Focus();
        }

        private void button6_Click(object sender, EventArgs e)
        {

        }

        private void button7_Click(object sender, EventArgs e)
        {
            if (textBox1.Text.Length > 0)
            {
                string text = textBox1.Text;
                textBox1.Text = text.Remove(text.Length - 1, 1);
            }
        }

        private void textBox2_TextChanged(object sender, EventArgs e)
        {

        }

        private void button9_Click(object sender, EventArgs e)
        {
            textBox1.Text += "1";
        }

        private void button10_Click(object sender, EventArgs e)
        {
            textBox1.Text += "2";
        }

        private void button11_Click(object sender, EventArgs e)
        {
            textBox1.Text += "3";
        }

        private void button13_Click(object sender, EventArgs e)
        {
            textBox1.Text += "4";
        }

        private void button14_Click(object sender, EventArgs e)
        {
            textBox1.Text += "5";
        }

        private void button15_Click(object sender, EventArgs e)
        {
            textBox1.Text += "6";
        }

        private void button17_Click(object sender, EventArgs e)
        {
            textBox1.Text += "7";
        }

        private void button18_Click(object sender, EventArgs e)
        {
            textBox1.Text += "8";
        }

        private void button19_Click_1(object sender, EventArgs e) 
        {
            textBox1.Text += "9";
        }

        private void button24_Click(object sender, EventArgs e)
        {
            textBox1.Text += "0";
        }

        private void button23_Click(object sender, EventArgs e)
        {
            textBox1.Text = CalcClass.ToggleSign(textBox1.Text);
        }

        private void button22_Click(object sender, EventArgs e)
        {
            textBox1.Text += "%";
        }

        private void button8_Click(object sender, EventArgs e)
        {
            textBox1.Text += "/";
        }

        private void button12_Click(object sender, EventArgs e)
        {
            textBox1.Text += "*";
        }

        private void button16_Click(object sender, EventArgs e)
        {
            textBox1.Text += "-";
        }

        private void button20_Click(object sender, EventArgs e)
        {
            textBox1.Text += "+";
        }

        private void button21_Click(object sender, EventArgs e)
        {
            string expression = textBox1.Text;
            try
            {
                object result = CalcClass.EvaluateExpression(expression);
                textBox2.Text = Convert.ToString(result);
            }
            catch (Exception ex)
            {
                textBox2.Text = "Error";
                MessageBox.Show("Invalid expression: " + ex.Message, "будет реализовано позже", MessageBoxButtons.OK, MessageBoxIcon.Error);
            }
        }

        private void label2_Click(object sender, EventArgs e)
        {

        }

        private void button27_Click(object sender, EventArgs e)
        {
            textBox1.Text += "sin(";
        }

        private void button26_Click(object sender, EventArgs e)
        {
            textBox1.Text += "cos(";
        }

        private void button25_Click(object sender, EventArgs e)
        {
            textBox1.Text += "square(";
        }

        private void button28_Click(object sender, EventArgs e)
        {
            textBox1.Text += "cube(";
        }

        private void button29_Click(object sender, EventArgs e)
        {
            textBox1.Text += ".";
        }
    }

    public class CalcClass
    {
        public static object EvaluateExpression(string expression)
        {
            //square(), cube(), sin(), cos()
            expression = Regex.Replace(expression, @"(sin|cos|square|cube)\(([^)]+)\)", match => {
                string functionName = match.Groups[1].Value;
                string argumentStr = match.Groups[2].Value;

                object argumentValObj = EvaluateExpression(argumentStr);
                double argumentVal = Convert.ToDouble(argumentValObj);

                double result = 0;

                switch (functionName)
                {
                    case "sin":
                        result = Math.Sin(argumentVal);
                        break;
                    case "cos":
                        result = Math.Cos(argumentVal);
                        break;
                    case "square":
                        result = argumentVal * argumentVal;
                        break;
                    case "cube":
                        result = argumentVal * argumentVal * argumentVal;
                        break;
                }

                return result.ToString(CultureInfo.InvariantCulture);
            });

            //для базовых операций (+, -, *, /, %)
            DataTable dt = new DataTable(); 
            dt.Locale = CultureInfo.InvariantCulture;

            return dt.Compute(expression, null);
        }

        public static long Mod(long a, long b)
        {
            return a % b;
        }

        public static string ToggleSign(string currentValue)
        {
            if (string.IsNullOrEmpty(currentValue))
            {
                return "0";
            }

            if (double.TryParse(currentValue, NumberStyles.Any, CultureInfo.InvariantCulture, out double number))
            {
                return (-number).ToString(CultureInfo.InvariantCulture);
            }

            return currentValue;
        }
    }
}