formmain.cs

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using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;

namespace SuperCalculator
{
    public partial class FormMain : Form
    {
        private double startAmount;
        private double yearRate;
        private int years;
        private string calculateFrequency;
        object sender = new object();
        EventArgs e = new EventArgs();
        public FormMain()
        {
            InitializeComponent();
            this.StartPosition = FormStartPosition.CenterScreen;
        }
        private void FormMain_Load(object sender, EventArgs e)
        {
            textBoxstartAmount.Focus();
        }
        private void FormMain_Shown(object sender, EventArgs e)
        {
            textBoxstartAmount.Focus();
        }

        private void groupBox1_Enter(object sender, EventArgs e)
        {
            //保证修改任意输入值时，不显示计算结果
            textBoxTotal.Clear();
        }
        /// <summary>
        /// 计算事件
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void buttonCalculate_Click(object sender, EventArgs e)
        {
            CaculateResult();
        }
        /// <summary>
        /// 计算事件实现函数
        /// </summary>
        private void CaculateResult()
        {
            string Amount = textBoxstartAmount.Text.Trim();
            try
            {
                startAmount = Double.Parse(Amount);

            }
            catch (Exception)
            {
                MessageBox.Show("含有非法字符，请重新输入！");
                return;
            }

            if (startAmount < 100.0)
                MessageBox.Show("存款金额不得低于100");

            string Rate = textBoxyearRate.Text.Trim();
            try
            {
                yearRate = Double.Parse(Rate) / 100;

            }
            catch (Exception)
            {
                MessageBox.Show("含有非法字符，请重新输入！");
                return;
            }
            if (yearRate >= 1.0)
                MessageBox.Show("利率输入错误!");
            try
            {
                years = Int32.Parse(textBoxyears.Text.Trim());

            }
            catch (Exception)
            {
                MessageBox.Show("含有非法字符，请重新输入！");
                return;
            }


            if (comboBoxcalculateFrequency.SelectedIndex == -1)
            {
                MessageBox.Show("请选择提供的利息计算方式");
                return;
            }
            calculateFrequency = comboBoxcalculateFrequency.SelectedItem.ToString();
            switch (calculateFrequency)
            {
                case "按月计息":
                    textBoxTotal.Text = Caculate(startAmount, yearRate / 12, years*12).ToString("f2");
                    break;
                case "按季度计息":
                    textBoxTotal.Text = Caculate(startAmount, yearRate / 4, years*4).ToString("f2");
                    break;
                case "按年计息":
                    textBoxTotal.Text = Caculate(startAmount, yearRate, years).ToString("f2");
                    break;
            }
        }
        /// <summary>
        /// 计算本息总额函数
        /// </summary>
        /// <param name="startAmount"></param>
        /// <param name="rate"></param>
        /// <param name="count"></param>
        /// <returns></returns>
        private double Caculate(double startAmount, double rate, int count)
        {
            return startAmount * Math.Pow((1 + rate), count);
        }
        private void textBox_KeyDown(object sender, KeyEventArgs e)
        {
            TextBox txt=(TextBox)sender;
            if (e.KeyCode == Keys.Enter)
            {
                switch(txt.Name)
                {
                    case "textBoxstartAmount":
                        textBoxyearRate.Focus();
                        break;
                    case "textBoxyearRate":
                        textBoxyears.Focus();
                        break;
                    case "textBoxyears":
                        comboBoxcalculateFrequency.Focus();
                        comboBoxcalculateFrequency.SelectedIndex = 0;
                        break;
                 } 
            }
           
        }

        private void textBox_TextChanged(object sender, EventArgs e)
        {
            textBoxTotal.Text = "";
        }

      
        private void comboBoxcalculateFrequency_SelectedIndexChanged(object sender, EventArgs e)
        {
            textBoxTotal.Text = "";
        }

        private void buttonCalculate_KeyDown(object sender, KeyEventArgs e)
        {
            if(e.KeyCode==Keys.Enter)
                CaculateResult();
        }

        private void comboBoxcalculateFrequency_KeyDown(object sender, KeyEventArgs e)
        {
            if (e.KeyCode == Keys.Enter)
                buttonCalculate.Focus();
        }
    }
}