计算器

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 JiSuanQi
{
public partial class Form1 : Form
{
int flagDot = 0;
bool pressDot = false;
float numFirst;
string oprator;
public Form1()
{
InitializeComponent();
}
private void delZero(string str)
{
//意思
if (str != "")
{

if (str.Substring(0, 1) == "0")
{
if (flagDot != 1)
{
txtShow.Text = "";
flagDot = 0;
}
}
}
}
private void btnZero_Click(object sender, EventArgs e)
{
delZero(txtShow.Text);
txtShow.Text = txtShow.Text + 0;
}

private void btnOne_Click(object sender, EventArgs e)
{
delZero(txtShow.Text);
txtShow.Text = txtShow.Text + 1;
}

private void btnPoint_Click(object sender, EventArgs e)
{
flagDot = 1;
delZero(txtShow.Text);
if (pressDot == false)
{
pressDot = true;
txtShow.Text = txtShow.Text + ".";
}
}

private void btnThree_Click(object sender, EventArgs e)
{
delZero(txtShow.Text);
txtShow.Text = txtShow.Text + 3;
}

private void btnTwo_Click(object sender, EventArgs e)
{
delZero(txtShow.Text);
txtShow.Text = txtShow.Text + 2;
}

private void btnFour_Click(object sender, EventArgs e)
{
delZero(txtShow.Text);
txtShow.Text = txtShow.Text + 4;
}

private void btnFive_Click(object sender, EventArgs e)
{
delZero(txtShow.Text);
txtShow.Text = txtShow.Text + 5;
}

private void btnSix_Click(object sender, EventArgs e)
{
delZero(txtShow.Text);
txtShow.Text = txtShow.Text + 6;
}

private void btnSeven_Click(object sender, EventArgs e)
{
delZero(txtShow.Text);
txtShow.Text = txtShow.Text + 7;
}

private void btnEight_Click(object sender, EventArgs e)
{
delZero(txtShow.Text);
txtShow.Text = txtShow.Text + 8;
}

private void btnNine_Click(object sender, EventArgs e)
{
delZero(txtShow.Text);
txtShow.Text = txtShow.Text + 9;
}

private void btnClear_Click(object sender, EventArgs e)
{
pressDot = false;
txtShow.Text = "";
}

private void btnSum_Click(object sender, EventArgs e)
{
numFirst = float.Parse(txtShow.Text);
oprator = "+";
txtShow.Text = "";
pressDot = false;

}
private void button14_Click(object sender, EventArgs e)
{
numFirst = float.Parse(txtShow.Text);
oprator = "*";
txtShow.Text = "";
pressDot = false;
}
private void button18_Click(object sender, EventArgs e)
{
numFirst = float.Parse(txtShow.Text);
oprator = "/";
txtShow.Text = "";
pressDot = false;
}

private void button15_Click(object sender, EventArgs e)
{
numFirst = float.Parse(txtShow.Text);
oprator = "-";
txtShow.Text = "";
pressDot = false;
}
private void btnResult_Click(object sender, EventArgs e)
{
float result;
if (oprator == "+")
{
result = numFirst + (float.Parse(txtShow.Text));
txtShow.Text = result.ToString();
}
else if (oprator== "-")
{
result=numFirst-(float.Parse(txtShow.Text));
txtShow.Text=result.ToString();
}

else if (oprator == "*")
{
result = numFirst * (float.Parse(txtShow.Text));
txtShow.Text = result.ToString();
}
else if (oprator == "/")
{

result = numFirst / (float.Parse(txtShow.Text));
txtShow.Text = result.ToString();
}
}

private void btnDelete_Click(object sender, EventArgs e)
{
string str = txtShow.Text, strText;
if (txtShow.Text.Length != 0)
{
strText = str.Substring(txtShow.Text.Length - 1, 1);
if (str.Substring(0, 1) == "0")
{
txtShow.Text = "";
pressDot = false;
}
txtShow.Text = str.Substring(0, txtShow.Text.Length - 1);

}

else
{
txtShow.Text = "";
}
flagDot = 0;
}

}
}

计算器

原文：http://www.cnblogs.com/abcdefg123/p/4856063.html