3、计算器（调用函数）

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 StudentForm
{
    public partial class JiSuanQi : Form
    {
        private decimal JieGuo;
        private string YunSuanFu;

        public JiSuanQi()
        {
            InitializeComponent();
        }
        private void JiaShuzi(string shuzi)
        {
            if (txtshuru.Text == "0")
            {
                txtshuru.Text = shuzi;
            }
            else
            {
                txtshuru.Text += shuzi;
            }
        }
        private void JiaYunSuanfu(string yunsuanfu)
        {
            if (txtjisuanshi.Text.Trim().Length == 0 && txtshuru.Text == "0")
            {
                label1.Text = "请先输入数字。";
            }
            else
            {
                if (YunSuanFu == "+")
                {
                    JieGuo += decimal.Parse(txtshuru.Text.Trim());
                }
                else if (YunSuanFu == "-")
                {
                    JieGuo -= decimal.Parse(txtshuru.Text.Trim());
                }
                else if (YunSuanFu == "*")
                {
                    JieGuo *= decimal.Parse(txtshuru.Text.Trim());
                }
                else if (YunSuanFu == "/")
                {
                    JieGuo /= decimal.Parse(txtshuru.Text.Trim());
                }
                else if (YunSuanFu == "%")
                {
                    JieGuo %= decimal.Parse(txtshuru.Text.Trim());
                }
                else
                {
                    JieGuo = decimal.Parse(txtshuru.Text.Trim());
                }

                txtjisuanshi.Text += txtshuru.Text;
                txtjisuanshi.Text += yunsuanfu;
                YunSuanFu = yunsuanfu;
                txtshuru.Text = "0";
            }
        }

        private void btndeng_Click(object sender, EventArgs e)
        {
            JiaYunSuanfu(btndeng.Text);
            txtshuru.Text  = JieGuo.ToString();
        }

        #region==数字button点击事件==
        private void btnling_Click(object sender, EventArgs e)
        {
            JiaShuzi(btnling.Text);
        }
        private void btnyi_Click(object sender, EventArgs e)
        {
            JiaShuzi(btnyi.Text);
        }
        private void btner_Click(object sender, EventArgs e)
        {
            JiaShuzi(btner.Text);
        }
        private void btnsan_Click(object sender, EventArgs e)
        {
            JiaShuzi(btnsan.Text);
        }
        private void btnsi_Click(object sender, EventArgs e)
        {
            JiaShuzi(btnsi.Text);
        }
        private void btnwu_Click(object sender, EventArgs e)
        {
            JiaShuzi(btnwu.Text);
        }
        private void btnliu_Click(object sender, EventArgs e)
        {
            JiaShuzi(btnliu.Text);
        }
        private void btnqi_Click(object sender, EventArgs e)
        {
            JiaShuzi(btnqi.Text);
        }
        private void btnba_Click(object sender, EventArgs e)
        {
            JiaShuzi(btnba.Text);
        }
        private void btnjiu_Click(object sender, EventArgs e)
        {
            JiaShuzi(btnjiu.Text);
        }
        #endregion

        private void btnClear_Click(object sender, EventArgs e)
        {
            txtshuru.Text = "0";
        }
        private void btndian_Click(object sender, EventArgs e)
        {
            if (txtshuru.Text.Contains("."))
            {
                label1.Text = "小数点只能输入一个";
            }
            else
            {
                txtshuru.Text += ".";
            }
        }

        #region==运算符点击事件==
        private void btnjia_Click(object sender, EventArgs e)
        {
            JiaYunSuanfu(btnjia.Text);
        }
        private void btnjian_Click(object sender, EventArgs e)
        {
            JiaYunSuanfu(btnjian.Text);
        }
        private void btncheng_Click(object sender, EventArgs e)
        {
            JiaYunSuanfu(btncheng.Text);
        }
        private void btnchu_Click(object sender, EventArgs e)
        {
            JiaYunSuanfu(btnchu.Text);
        }
        private void btnmo_Click(object sender, EventArgs e)
        {
            JiaYunSuanfu(btnmo.Text);
        }
        #endregion

        private void btnchexiao_Click(object sender, EventArgs e)
        {
            txtshuru.Text = txtshuru.Text.Substring(0, txtshuru.Text.Length - 1);
        }
    }
}