C#作业——表达式计算器+小数+运算符优先级

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 WindowsFormsApplication1
{
public partial class Form1 : Form
{
public String expression;
public class op
{
public char symbol;//符号
public int grade;//优先级
public op(char sym)
{
symbol = sym;
if ((symbol == '+') || (symbol == '-'))
grade = 0;
else
grade = 1;
}

public double calculate(double p1,double p2)
{
if (symbol == '+')
return p1 + p2;
else if (symbol == '-')
return p1 - p2;
else if (symbol == '*')
return p1 * p2;
else if (symbol == '/')
return p1 / p2;
else
return 0;

}

}

public class datanum
{
public double number;
public bool isdeleted = false;
public datanum(double num)
{
number = num;
}
public void delete()
{
isdeleted = true;
}
}

public Form1()
{
InitializeComponent();
}

private void Form1_Load(object sender, EventArgs e)
{

}

private void textBox1_TextChanged(object sender, EventArgs e)
{
expression = textBox1.Text;
}

private void button1_Click(object sender, EventArgs e)
{
textBox1.Text = expression + "=" + Result(expression);
}
private double Result(String expression)
{
int length = expression.Length;
char[] a = expression.ToCharArray(0, length);
datanum[] data = new datanum[10];
op[] oper = new op[10];
int datacount = 0, opercount = 0;
double temp = 0;
int dicimal = -1;
double tempdi = 1;
for (int m = 0; m < length; m++)
{

if (Char.IsDigit(a[m]) == true)
{

if (dicimal == -1)
{
temp *= 10;
temp += a[m] - '0';
}
else
{
dicimal++;
for (int q = 0; q < dicimal; q++)
tempdi = tempdi * 0.1;
temp = temp + (a[m] - '0') * tempdi;
tempdi = 1;
}

}
else if (a[m] == '.')
{
dicimal = 0;
}
else
{
dicimal = -1;
tempdi = 1;
data[datacount] = new datanum(temp);
datacount++;
temp = 0;
oper[opercount] = new op(a[m]);
opercount++;
}
}

data[datacount] = new datanum(temp);//最后一个数
datacount++;

double n=0;
int temp1;
int tempgrade = 1;
int[] lossdata = new int[10];
while(tempgrade>=0)
{
for (temp1 = 0; temp1 < opercount; temp1++)
{
if (oper[temp1].grade == tempgrade)
{
int pa = temp1;
int pb = temp1 + 1;
while(data[pa].isdeleted==true)
{
pa--;
}
while(data[pb].isdeleted==true)
{
pb++;
}

data[pa].number=oper[temp1].calculate(data[pa].number, data[pb].number);
n = data[pa].number;
data[pb].delete();

}

}
tempgrade--;
}
return n;
}

private void button2_Click(object sender, EventArgs e)
{
textBox1.Clear();
}
}
}