[C#] 22일차 - 161. WinForm 윈도우 표준 계산기

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 A161_WinformCalc
{
    public partial class Form1 : Form
    {
        private double saved;           // txtResult에 있는 값 저장
        private double memory;          // 메모리에 저장된 값
        private char op = '\0';         // 현재 계산할 op
        private bool opFlag = false;    // 연산자를 누른 후인지 체크하는 flag
        private bool memFlag;           // 메모리 버튼을 누른 후인지 체크
        private bool percentFlag;       // % 처리를 위한 flag
        public Form1()
        {
            InitializeComponent();

            // MC, MR 버튼 false
            btnMC.Enabled = false;
            btnMR.Enabled = false;
        }

        // 모든 숫자 버튼을 하나로 처리하는 메소드
        private void btn_Click(object sender, EventArgs e)
        {
            Button btn = sender as Button;
            string s = btn.Text;    // 버튼의 Text를 s로 저장

            if (txtResult.Text == "0" || opFlag == true || memFlag == true)
            {
                txtResult.Text = s;
                opFlag = false;
                memFlag = false;
            }
            else
                txtResult.Text = txtResult.Text + s;

            txtResult.Text = GroupSeparator(txtResult.Text); // 3자리마다 , 넣어주는 메소드 적용
        }

        // 연산자
        private void btnOp_Click(object sender, EventArgs e)
        {
            Button btn = sender as Button;

            saved = Double.Parse(txtResult.Text);
            txtExp.Text += txtResult.Text + " " + btn.Text + " "; // 위에 연산창에 추가 
            op = btn.Text[0];
            opFlag = true;
            percentFlag = true;
        }

        // = 버튼, 계산 수행
        private void btnEqual_Click(object sender, EventArgs e)
        {
            Double value = Double.Parse(txtResult.Text);
            switch (op)
            {
                case '+':
                    txtResult.Text = (saved + value).ToString();
                    break;
                case '-':
                    txtResult.Text = (saved - value).ToString();
                    break;
                case '*':
                    txtResult.Text = (saved * value).ToString();
                    break;
                case '/':
                    txtResult.Text = (saved / value).ToString();
                    break;
            }
            txtResult.Text = GroupSeparator(txtResult.Text);
            txtExp.Text = "";
        }

        private void btnDot_Click(object sender, EventArgs e)
        {
            if (txtResult.Text.Contains("."))
                return;
            else
                txtResult.Text += ".";
        }

        private string GroupSeparator(string s)
        {
            int pos = 0;
            double v = Double.Parse(s);

            if (s.Contains("."))
            {
                pos = s.Length - s.IndexOf('.');
                if (pos == 1) // 맨 뒤에 소수점이 있으면 그대로 리턴
                    return s;
                string formatStr = "{0:N" + (pos - 1) + "}";
                s = string.Format(formatStr, v);
            } else
            {
                s = string.Format("{0:N0}", v);
            }
            return s;
        }

        // 제곱근
        private void btnSqrt_Click(object sender, EventArgs e)
        {
            txtExp.Text = "V(" + txtResult.Text + ") ";
            txtResult.Text = Math.Sqrt(Double.Parse(txtResult.Text)).ToString();
            txtResult.Text = GroupSeparator(txtResult.Text);
        }

        // 제곱
        private void btnSqr_Click(object sender, EventArgs e)
        {
            txtExp.Text = "sqr(" + txtResult.Text + ") ";
            txtResult.Text = (Double.Parse(txtResult.Text) * Double.Parse(txtResult.Text)).ToString();
            txtResult.Text = GroupSeparator(txtResult.Text);
        }

        // 역수
        private void btnRecip_Click(object sender, EventArgs e)
        {
            txtExp.Text = "1 / (" + txtResult.Text + ") ";
            txtResult.Text = (1 / Double.Parse(txtResult.Text)).ToString();
            txtResult.Text = GroupSeparator(txtResult.Text);
        }

        // 부호버튼
        private void btnPlusMinus_Click(object sender, EventArgs e)
        {
            double v = Double.Parse(txtResult.Text);
            txtResult.Text = (-v).ToString();
            txtResult.Text = GroupSeparator(txtResult.Text);
        }

        private void btnPercent_Click(object sender, EventArgs e)
        {
            if(percentFlag == true)
            {
                double p = Double.Parse(txtResult.Text);
                p = saved * p / 100.0;
                txtResult.Text = p.ToString();
                txtExp.Text += txtResult.Text;
                percentFlag = false;
            }
        }

        // 메모리 저장
        private void btnMR_Click(object sender, EventArgs e)
        {
            txtResult.Text = memory.ToString();
            memFlag = true;
            txtResult.Text = GroupSeparator(txtResult.Text);
        }

        private void btnMC_Click(object sender, EventArgs e)
        {
            txtResult.Text = "0";
            memory = 0;
            btnMR.Enabled = false;
            btnMC.Enabled = false;
        }

        private void btnMPlus_Click(object sender, EventArgs e)
        {
            memory += Double.Parse(txtResult.Text);
        }

        private void btnMMinus_Click(object sender, EventArgs e)
        {
            memory -= double.Parse(txtResult.Text);
        }

        private void btnCE_Click(object sender, EventArgs e)
        {
            txtResult.Text = "0";
        }

        // 초기화
        private void btnC_Click(object sender, EventArgs e)
        {
            txtResult.Text = "0";
            txtExp.Text = "";
            saved = 0;
            op = '\0';
            opFlag = false;
            percentFlag = false;
        }

        // 맨 뒤의 한 글자 지우기
        private void btnDelete_Click(object sender, EventArgs e)
        {
            txtResult.Text = txtResult.Text.Remove(txtResult.Text.Length - 1);
            if (txtResult.Text.Length == 0)
                txtResult.Text = "0";
        }
    }
}