我创建了计算器。它最终运行但是一旦我开始输入任何不正确的东西它会抛出FormatException。我在下面附上我的代码，请建议我如何在我的程序中处理异常。
MyCalculator.cs
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
namespace MyCalculator
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
float number, answer;
int count;
public void disable() //create new method to disable calculator
{
//follow are disable when call we disable() function
Display.Enabled = false;
On.Show();//it will be still display
offbutton.Hide(); //it will be hide
back.Enabled = false;
clear.Enabled = false;
Add.Enabled = false;
Sub.Enabled = false;
Multiply.Enabled = false;
Divide.Enabled = false;
Zero.Enabled = false;
One.Enabled = false;
Two.Enabled = false;
Three.Enabled = false;
Four.Enabled = false;
Five.Enabled = false;
Six.Enabled = false;
Seven.Enabled = false;
Eight.Enabled = false;
Nine.Enabled = false;
equal.Enabled = false;
Point.Enabled = false;
}
public void enable() //create new method to enable calculator
{
//follow are enable we call enable() function
Display.Enabled = true;
On.Hide();//it will be hide
offbutton.Show();//it will be still display
back.Enabled = true;
clear.Enabled = true;
Add.Enabled = true;
Sub.Enabled = true;
Multiply.Enabled = true;
Divide.Enabled = true;
Zero.Enabled = true;
One.Enabled = true;
Two.Enabled = true;
Three.Enabled = true;
Four.Enabled = true;
Five.Enabled = true;
Six.Enabled = true;
Seven.Enabled = true;
Eight.Enabled = true;
Nine.Enabled = true;
equal.Enabled = true;
Point.Enabled = true;
}
private void Point_Click(object sender, EventArgs e)
{
//Display dot(.) in textbox when press dot(.) button with red color
Display.Text = Display.Text+".";
Display.ForeColor = Color.Red;
}
private void Zero_Click(object sender, EventArgs e)
{
//Display zero(0) in textbox when press zero(0) button with red color
Display.Text = Display.Text + 0;
Display.ForeColor = Color.Red;
}
private void One_Click(object sender, EventArgs e)
{
//Display 1 in textboc when press 1 button with red color
Display.Text = Display.Text + 1;
Display.ForeColor = Color.Red;
}
private void Two_Click(object sender, EventArgs e)
{
//Display 2 in textboc when press 2 button with red color
Display.Text = Display.Text + 2;
Display.ForeColor = Color.Red;
}
private void Three_Click(object sender, EventArgs e)
{
//Display 3 in textboc when press 3 button with red color
Display.Text = Display.Text + 3;
Display.ForeColor = Color.Red;
}
private void Four_Click(object sender, EventArgs e)
{
//Display 4 in textboc when press 4 button with red color
Display.Text = Display.Text + 4;
Display.ForeColor = Color.Red;
}
private void Five_Click(object sender, EventArgs e)
{
//Display 5 in textboc when press 5 button with red color
Display.Text = Display.Text + 5;
Display.ForeColor = Color.Red;
}
private void Six_Click(object sender, EventArgs e)
{
//Display 6 in textboc when press 6 button with red color
Display.Text = Display.Text + 6;
Display.ForeColor = Color.Red;
}
private void Seven_Click(object sender, EventArgs e)
{
//Display 7 in textboc when press 7 button with red color
Display.Text = Display.Text + 7;
Display.ForeColor = Color.Red;
}
private void Eight_Click(object sender, EventArgs e)
{
//Display 8 in textboc when press 8 button with red color
Display.Text = Display.Text + 8;
Display.ForeColor = Color.Red;
}
private void Nine_Click(object sender, EventArgs e)
{
//Display 9 in textboc when press 9 button with red color
Display.Text = Display.Text + 9;
Display.ForeColor = Color.Red;
}
private void offbutton_Click(object sender, EventArgs e)//off button
{
disable(); //call disable to off calculator
}
private void On_Click(object sender, EventArgs e) //on button
{
enable(); //call enable function to on calculator
}
public void compute()
{
switch (count) //creating switch statement
{
case 1:
answer = number + float.Parse(Display.Text);
//it performs addition
Display.Text = answer.ToString();
//converts float into string
break;
case 2:
answer = number - float.Parse(Display.Text);
//it performs subtraction
Display.Text = answer.ToString(); //converts float into string
break;
case 3:
answer = number * float.Parse(Display.Text); //it performs Multiplication
Display.Text = answer.ToString(); //converts float into string
break;
case 4:
answer = number / float.Parse(Display.Text); //it performs Division
Display.Text = answer.ToString(); //converts float into string
break;
default:
break;
}
}
private void Add_Click(object sender, EventArgs e)
{
number = float.Parse(Display.Text);
Display.Clear(); //clear the textbox
Display.Focus(); //focus on textbox after clear
count = 1; //count store case
label1.Text = number.ToString() + "+"; //display text on lable
}
private void Sub_Click(object sender, EventArgs e)
{
number = float.Parse(Display.Text);
Display.Clear(); //clear the textbox
Display.Focus(); //focus on textbox after clear
count = 2; //count store switch case value
label1.Text = number.ToString() + "-"; //display text on lable
}
private void Multiply_Click(object sender, EventArgs e)
{
number = float.Parse(Display.Text);
Display.Clear(); //clear the textbox
Display.Focus(); //focus on textbox after clear
count = 3; //count store switch case value
label1.Text = number.ToString() + "*"; //display text on lable
}
private void Divide_Click(object sender, EventArgs e)
{
number = float.Parse(Display.Text);
Display.Clear(); //clear the textbox
Display.Focus(); //focus on textbox after clear
count = 4; //count store switch case value
label1.Text = number.ToString() + "/"; //display text on lable
}
private void equal_Click(object sender, EventArgs e)
{
compute();//call compute function to perform such operations
label1.Text = "";//clear the text on the lable
}
private void clear_Click(object sender, EventArgs e)//clear button
{
Display.Text = ""; //clear the textbox
}
private void back_Click(object sender, EventArgs e)//backspace button
{
int length = Display.TextLength - 1;
string text = Display.Text;
Display.Clear();
for (int i = 0; i < length; i++)
Display.Text = Display.Text + text[i];
}
}
}
请尽快帮助我
答案 0 :(得分：0)
如何使用
if(!float.TryParse(Display.Text, out number))
return;
//rest of your code
答案 1 :(得分：-1)
使用Try {} catch {}！
基本上你可以随处使用它。我建议您在使用logik时尽量使用它，以使您的程序尽可能稳定。它的主要任务是做错误处理（强烈推荐）。因此，当使用TryCatch（如下所示的示例）在catch块中执行某些操作时。显示MessageBox，显示自制的errorMessage或向用户显示ex.Message。
在你的情况下，我会实现它：
例如：
try
{
//Do your logic here !
}
catch(Exception ex) //Here you can catch any type of Exception
{ //like InvalidFormatException, and even print out ex.Message
//Do something
//Logging, MessageBox(Invalid operation ..), ...
}
请参阅https://msdn.microsoft.com/de-de/library/0yd65esw.aspx和
https://msdn.microsoft.com/library/ms229005%28v=vs.100%29.aspx了解更多信息。