winform 计算器 两步走

namespace WindowsFormsApplication4
{
    public partial class Form2 : Form
    {
        public Form2()
        {
            InitializeComponent();
        }

        //记录是否刚点过运算符
        private bool isok = true;
        //记录结果
        private decimal Sum;
        //记录上一次的运算符
        private string PreYunsuanfu;
        //记录表达式
        private string Biaodashi;

        private void Form2_Load(object sender, EventArgs e)
        {

        }

        private void btnling_Click(object sender, EventArgs e)
        {
            if (isok)
            {
                txtshuru.Text = "0";
               // isok = false;
            }
            else
            {
                txtshuru.Text += "0";
            }
        }

        private void btnyi_Click(object sender, EventArgs e)
        {
            if (isok)
            {
                txtshuru.Text = "1";
                isok = false;
            }
            else
            {
                txtshuru.Text += "1";
            }
        }

        private void btner_Click(object sender, EventArgs e)
        {
            if (isok)
            {
                txtshuru.Text = "2";
                isok = false;
            }
            else
            {
                txtshuru.Text += "2";
            }
        }

        private void btnsan_Click(object sender, EventArgs e)
        {
             if (isok)
            {
                txtshuru.Text = "3";
                isok = false;
            }
            else
            {
                txtshuru.Text += "3";
            }
        }

        private void btnsi_Click(object sender, EventArgs e)
        {
            if (isok)
            {
                txtshuru.Text = "4";
                isok = false;
            }
            else
            {
                txtshuru.Text += "4";
            }
        }

        private void btnwu_Click(object sender, EventArgs e)
        {
            if (isok)
            {
                txtshuru.Text = "5";
                isok = false;
            }
            else
            {
                txtshuru.Text += "5";
            }
        }

        private void btnliu_Click(object sender, EventArgs e)
        {
            if (isok)
            {
                txtshuru.Text = "6";
                isok = false;
            }
            else
            {
                txtshuru.Text += "6";
            }
        }

        private void btnqi_Click(object sender, EventArgs e)
        {
            if (isok)
            {
                txtshuru.Text = "7";
                isok = false;
            }
            else
            {
                txtshuru.Text += "7";
            }
        }

        private void btnba_Click(object sender, EventArgs e)
        {
            if (isok)
            {
                txtshuru.Text = "8";
                isok = false;
            }
            else
            {
                txtshuru.Text += "8";
            }
        }

        private void btnjiu_Click(object sender, EventArgs e)
        {
            if (isok)
            {
                txtshuru.Text = "9";
                isok = false;
            }
            else
            {
                txtshuru.Text += "9";
            }
        }

        private void btnjia_Click(object sender, EventArgs e)
        {
            if (PreYunsuanfu == null)
            {
                Sum = decimal.Parse(txtshuru.Text);
                Biaodashi = txtshuru.Text;
            }
            else
            {
                if (!isok)
                {
                    if (PreYunsuanfu == "+")
                    {
                        Sum = Sum + decimal.Parse(txtshuru.Text);
                    }
                    if (PreYunsuanfu == "-")
                    {
                        Sum = Sum - decimal.Parse(txtshuru.Text);
                    }
                    if (PreYunsuanfu == "*")
                    {
                        Sum = Sum * decimal.Parse(txtshuru.Text);
                    }
                    if (PreYunsuanfu == "/")
                    {
                        Sum = Sum / decimal.Parse(txtshuru.Text);
                    }
                    if (PreYunsuanfu == "%")
                    {
                        Sum = Sum % decimal.Parse(txtshuru.Text);
                    }

                    Biaodashi = Biaodashi + PreYunsuanfu + txtshuru.Text;
                }
            }

            txtjisuanshi.Text = Biaodashi + "+";
            PreYunsuanfu = "+";
            isok = true;
            txtshuru.Text = Sum.ToString();
        }

        private void btnjian_Click(object sender, EventArgs e)
        {
            if (PreYunsuanfu == null)
            {
                Sum = decimal.Parse(txtshuru.Text);
                Biaodashi = txtshuru.Text;
            }
            else
            {
                if (!isok)
                {
                    if (PreYunsuanfu == "+")
                    {
                        Sum = Sum + decimal.Parse(txtshuru.Text);
                    }
                    if (PreYunsuanfu == "-")
                    {
                        Sum = Sum - decimal.Parse(txtshuru.Text);
                    }
                    if (PreYunsuanfu == "*")
                    {
                        Sum = Sum * decimal.Parse(txtshuru.Text);
                    }
                    if (PreYunsuanfu == "/")
                    {
                        Sum = Sum / decimal.Parse(txtshuru.Text);
                    }
                    if (PreYunsuanfu == "%")
                    {
                        Sum = Sum % decimal.Parse(txtshuru.Text);
                    }

                    Biaodashi = Biaodashi + PreYunsuanfu + txtshuru.Text;
                }
            }

            txtjisuanshi.Text = Biaodashi + "-";
            PreYunsuanfu = "-";
            isok = true;
            txtshuru.Text = Sum.ToString();
        }

        private void btncheng_Click(object sender, EventArgs e)
        {
            if (PreYunsuanfu == null)
            {
                Sum = decimal.Parse(txtshuru.Text);
                Biaodashi = txtshuru.Text;
            }
            else
            {
                if (!isok)
                {
                    if (PreYunsuanfu == "+")
                    {
                        Sum = Sum + decimal.Parse(txtshuru.Text);
                    }
                    if (PreYunsuanfu == "-")
                    {
                        Sum = Sum - decimal.Parse(txtshuru.Text);
                    }
                    if (PreYunsuanfu == "*")
                    {
                        Sum = Sum * decimal.Parse(txtshuru.Text);
                    }
                    if (PreYunsuanfu == "/")
                    {
                        Sum = Sum / decimal.Parse(txtshuru.Text);
                    }
                    if (PreYunsuanfu == "%")
                    {
                        Sum = Sum % decimal.Parse(txtshuru.Text);
                    }

                    Biaodashi = Biaodashi + PreYunsuanfu + txtshuru.Text;
                }
            }

            txtjisuanshi.Text = Biaodashi + "*";
            PreYunsuanfu = "*";
            isok = true;
            txtshuru.Text = Sum.ToString();
        }

        private void btnchu_Click(object sender, EventArgs e)
        {
            if (PreYunsuanfu == null)
            {
                Sum = decimal.Parse(txtshuru.Text);
                Biaodashi = txtshuru.Text;
            }
            else
            {
                if (!isok)
                {
                    if (PreYunsuanfu == "+")
                    {
                        Sum = Sum + decimal.Parse(txtshuru.Text);
                    }
                    if (PreYunsuanfu == "-")
                    {
                        Sum = Sum - decimal.Parse(txtshuru.Text);
                    }
                    if (PreYunsuanfu == "*")
                    {
                        Sum = Sum * decimal.Parse(txtshuru.Text);
                    }
                    if (PreYunsuanfu == "/")
                    {
                        Sum = Sum / decimal.Parse(txtshuru.Text);
                    }
                    if (PreYunsuanfu == "%")
                    {
                        Sum = Sum % decimal.Parse(txtshuru.Text);
                    }

                    Biaodashi = Biaodashi + PreYunsuanfu + txtshuru.Text;
                }
            }

            txtjisuanshi.Text = Biaodashi + "/";
            PreYunsuanfu = "/";
            isok = true;
            txtshuru.Text = Sum.ToString();
        }

        private void btnmo_Click(object sender, EventArgs e)
        {
            if (PreYunsuanfu == null)
            {
                Sum = decimal.Parse(txtshuru.Text);
                Biaodashi = txtshuru.Text;
            }
            else
            {
                if (!isok)
                {
                    if (PreYunsuanfu == "+")
                    {
                        Sum = Sum + decimal.Parse(txtshuru.Text);
                    }
                    if (PreYunsuanfu == "-")
                    {
                        Sum = Sum - decimal.Parse(txtshuru.Text);
                    }
                    if (PreYunsuanfu == "*")
                    {
                        Sum = Sum * decimal.Parse(txtshuru.Text);
                    }
                    if (PreYunsuanfu == "/")
                    {
                        Sum = Sum / decimal.Parse(txtshuru.Text);
                    }
                    if (PreYunsuanfu == "%")
                    {
                        Sum = Sum % decimal.Parse(txtshuru.Text);
                    }

                    Biaodashi = Biaodashi + PreYunsuanfu + txtshuru.Text;
                }
            }

            txtjisuanshi.Text = Biaodashi + "%";
            PreYunsuanfu = "%";
            isok = true;
            txtshuru.Text = Sum.ToString();
        }

        private void btnClear_Click(object sender, EventArgs e)
        {
            txtshuru.Text = "0";
            txtjisuanshi.Text = "";
            isok = true;
            PreYunsuanfu = null;
            Sum = 0;
            Biaodashi = "";
        }

        private void btnchexiao_Click(object sender, EventArgs e)
        {
            if (!isok)
            {
                if (txtshuru.Text.Length == 1)
                {
                    txtshuru.Text = "0";
                    isok = true;
                }
                else
                {
                    txtshuru.Text = txtshuru.Text.Substring(0, txtshuru.Text.Length - 1);
                }
            }
        }

        private void btndian_Click(object sender, EventArgs e)
        {
            if (txtshuru.Text == "0")
            {
                txtshuru.Text = "0.";
            }
            if (!isok  && !txtshuru.Text.Contains("."))
            {
                txtshuru.Text += ".";
            }
            isok = false;
        }

        private void btndeng_Click(object sender, EventArgs e)
        {
            txtjisuanshi.Text = "";
            if (PreYunsuanfu == "+")
            {
                Sum = Sum + decimal.Parse(txtshuru.Text);
            }
            if (PreYunsuanfu == "-")
            {
                Sum = Sum - decimal.Parse(txtshuru.Text);
            }
            if (PreYunsuanfu == "*")
            {
                Sum = Sum * decimal.Parse(txtshuru.Text);
            }
            if (PreYunsuanfu == "/")
            {
                Sum = Sum / decimal.Parse(txtshuru.Text);
            }
            if (PreYunsuanfu == "%")
            {
                Sum = Sum % decimal.Parse(txtshuru.Text);
            }
            txtshuru.Text = Sum.ToString();
            isok = true;
            Biaodashi = "";
            Sum = 0;
            PreYunsuanfu = null;
        }

        private void btnzhengfu_Click(object sender, EventArgs e)
        {
            if (!isok)
            {
                if (decimal.Parse(txtshuru.Text) > 0)
                {
                    txtshuru.Text = "-" + txtshuru.Text;
                }
                else
                {
                    txtshuru.Text = txtshuru.Text.Substring(1);
                }
            }
        }
    }
}

TWO  button事件

namespace FirstForm
{
    public partial class JiSuanQi : Form
    {
        public JiSuanQi()
        {
            InitializeComponent();
        }

        private double sum=0;//记录上一步的运算结果
        private string biaodashi;//点击运算符之前的算式
        private string Preyunsuanfu;//存放之前的运算符
        private bool isok = true;//用来判断是否刚刚点过运算符
        private void btnling_Click(object sender, EventArgs e)
        {
            Button btn = (Button)sender;
            if (isok)
            {
                txtshuru.Text = btn.Text;
                isok = false;
            }
            else
            {
                txtshuru.Text += btn.Text;
            }

        }
        private void btnjia_Click(object sender, EventArgs e)
        {
            Button btn = (Button)sender;
            string yunsuanfu = btn.Text;
            if (Preyunsuanfu == null)
            {
                biaodashi += txtshuru.Text;
                sum = double.Parse(txtshuru.Text);
            }
            else
            {
                if (!isok)
                {
                    if (Preyunsuanfu == "+")
                    {
                        sum += double.Parse(txtshuru.Text);
                    }
                    if (Preyunsuanfu == "-")
                    {
                        sum -= double.Parse(txtshuru.Text);
                    }
                    if (Preyunsuanfu == "*")
                    {
                        sum *= double.Parse(txtshuru.Text);
                    }
                    if (Preyunsuanfu == "/")
                    {
                        sum /= double.Parse(txtshuru.Text);
                    }
                    if (Preyunsuanfu == "%")
                    {
                        sum %= double.Parse(txtshuru.Text);
                    }

                    biaodashi = biaodashi+ Preyunsuanfu + txtshuru.Text;
                    txtshuru.Text = sum.ToString();
                }
            }
            txtjisuanshi.Text = biaodashi + yunsuanfu;
            Preyunsuanfu = yunsuanfu;
            isok = true;

        }

    }
}