윈폼을 이용해서 간단한 계산기(DotNetCalc) 만들기

==> Program.cs


using System;
using System.Collections.Generic;
using System.Linq;
using System.Windows.Forms;

namespace DotNetCalc
{
    static class Program
    {
        /// <summary>
        /// 해당 응용 프로그램의 주 진입점입니다.
        /// </summary>
        [STAThread]
        static void Main()
        {
            Application.EnableVisualStyles();
            Application.SetCompatibleTextRenderingDefault(false);
            Application.Run(new MainForm());
        }
    }
}



==============================================================================================




==> MainForm.cs



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 DotNetCalc
{
    public partial class MainForm : Form
    {
        private string buffer; // 입력된 문자열들을 묶어줄 그릇

        public MainForm()
        {
            InitializeComponent();
        }
               
        private void btnCommand_Click(object sender, EventArgs e)
        {
            Button btn = sender as Button;

    #region 각각의 버튼 클릭시 해당 문자열을 buffer에 담기

  if (btn == btnOne)
         {
          buffer += "1";
         }
            else if (btn == btnTwo)
         {
                buffer += "2";
         }
            else if (btn == btnThree)
         {
                buffer += "3";
         }
            else if (btn == btnFour)
         {
                buffer += "4";
         }
            else if (btn == btnFive)
         {
                buffer += "5";
         }
            else if (btn == btnSix)
         {
                buffer += "6";
         }
            else if (btn == btnSeven)
         {
                buffer += "7";
         }
            else if (btn == btnEight)
         {
                buffer += "8";
         }
            else if (btn == btnNine)
         {
                buffer += "9";
         }
                else if (btn == btnZero)
         {
                buffer += "0";
         }
            else if (btn == btnLeft)
         {
                buffer += "(";
         }
            else if (btn == btnRight)
         {
                buffer += ")";
         }
            else if (btn == btnPlus)
         {
                buffer += " + ";
         }
            else if (btn == btnMinus)
         {
                buffer += " - ";
         }
            else if (btn == btnMultiply)
         {
                buffer += " * ";
         }
            else if (btn == btnDivide)
         {
                buffer += " / ";
         }
            else if (btn == btnPoint)
         {
                buffer += ".";
         }

 #endregion

            txtExpression.Text = buffer;
        }

        private void btnClear_Click(object sender, EventArgs e)
        {
            buffer = String.Empty;
            txtExpression.Text = "";
        }

        private void btnBackspace_Click(object sender, EventArgs e)
        {
            if (buffer.Length > 0)
            {
                // 마지막 한자리 삭제
                buffer = buffer.Substring(0, buffer.Length - 1);
                txtExpression.Text = buffer;
            }
        }

        // 문자열로 지정된 수식을 실제 수식으로 변환 후 결과값 계산
        private void btnEnter_Click(object sender, EventArgs e)
        {
            // 문자열 수식에서 공백 제거
            string temp = txtExpression.Text.Replace(" ", "");
            if (String.IsNullOrEmpty(temp))
            {
                MessageBox.Show("수식을 입력하시오.");
                return;
            }
            this.txtExpression.Text += " = \r\n\r\n" + MakeExpression(ref temp).ToString();
            buffer = ""; // 버퍼 초기화(= 최상위 buffer는 널값으로 초기화)
        }

       
        // MakeExpression : 결과값 텍스트박스에 출력, 공백이 제거되어 넘겨져온 수식을 계산한다.
        /// <summary>
        /// [4] 문자열로 지정된 계산식을 실제 계산식으로 변경
        /// </summary>
        /// <param name="str">3 * (2 + 3)</param>
        /// <returns>15</returns>
        public double MakeExpression(ref string str)
        {
            int index = 0; // 문자 위치
            // 구문 결과값 가져오기
            double value = Sentence(ref str, ref index);
            while (index < str.Length)
            {
                switch (str[index])
                {
                    case '+':
                        ++(index);
                        value += Sentence(ref str, ref index);
                        break;
                    case '-':
                        ++(index);
                        value -= Sentence(ref str, ref index);
                        break;
                    default: // 엉뚱한 값이 들어오는 경우
                        MessageBox.Show("잘못된 구문입니다.");
                        break;
                }
            }
            return value;
        }

        /// <summary>
        /// [3] 하나의 완성된 수식을 계산하는 메서드
        ///     (3 * 5) = 15
        /// </summary>
        /// <param name="str">(3 * 5)</param>
        /// <param name="index">0</param>
        /// <returns>15</returns>
        public double Sentence(ref string str, ref int index)
        {
            double value = GetNumber(ref str, ref index); // 첫번째 숫자
            while (index < str.Length)
            {
                if (str[index] == '*')
                {
                    ++(index);
                    value *= GetNumber(ref str, ref index);
                }
                else if (str[index] == '/')
                {
                    ++(index);
                    value /= GetNumber(ref str, ref index);
                }
                else
                    break;
            }
            return value;
        }
       
       
        /// <summary>
        /// [2] 문자열에서 첫번째 나오는 숫자형을 실제 숫자형으로 변환시켜주는 함수
        /// </summary>
        /// <param name="str">(12.34+3)</param>
        /// <param name="index">1</param>
        /// <returns>12.34(숫자형)</returns>       
        public double GetNumber(ref string str, ref int index)
        {
            double value = 0.0;

            // GetSubstring함수 호출해서 괄호안에 있는 문자열만 가져오기
            if (str[index] == '(')
         {
                ++(index);
                string substr = GetSubstring(ref str, ref index);
                return MakeExpression(ref substr); // 괄호안의 수식만 먼저 계산
         }
            while ((index < str.Length) && Char.IsDigit(str, index))
            {
                value = 10.0 * value + Char.GetNumericValue(str[(index)]);
                ++(index);
            }
            if ((index == str.Length) || str[index] != '.') return value;
         double factor = 1.0;
            ++(index);

            while ((index < str.Length) && Char.IsDigit(str, index))
            {
                factor *= 0.1;
                value = value + Char.GetNumericValue(str[index]) * factor;
                ++(index);
            }

            return value;
        }
        

        //[1] 괄호안에 있는 하위 문자열을 추출(하는 함수 만들기) : (123+5) => 123+5만 추출
        public string GetSubstring(ref string str, ref int index) // GetSubstring : 괄호안의 문자열을 추출하는 함수
        {
            string substr = ""; // 하위 문자열 저장
            int numL = 0; // 왼쪽 괄호의 개수
            int bufindex = index; // 인덱스의 시작 값
            while (index < str.Length)
            {
                switch (str[index])
             {
                    case ')' :
                        if (numL == 0)
                     {
                            char[] substrChars = new char[index - bufindex];
                            str.CopyTo(bufindex, substrChars, 0, substrChars.Length);
                            substr = new String(substrChars);
                            ++(index);
                            return substr;
                     }
                        else
                            numL--; // 왼쪽 괄호와 일치하는 오른쪽 괄호가 나타날 시 감소
                        break;

                    case '(' :
                        numL++;
                        break;
                }
                ++(index);
            }
            MessageBox.Show("잘못된 구문입니다.");
            return substr;
     }
    }
}

 

< 실행결과 >

DotNetCalc.zip