计算器总失败

Question

我正在使用 C# 编写一个计算器。

namespace Calculator
{
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
        }
        public void Total(string num)   
        {
            lblTotal.Content = Convert.ToString(lblTotal.Content) + num;
        }
        private void one_Click(object sender, RoutedEventArgs e)
        {
            Total( Convert.ToString(1) );
        }
        private void two_Click(object sender, RoutedEventArgs e)
        {
            Total( Convert.ToString(2) );
        }
        private void three_Click(object sender, RoutedEventArgs e)
        {
            Total( Convert.ToString(3) );
        }
        private void four_Click(object sender, RoutedEventArgs e)
        {
            Total( Convert.ToString(4) );
        }
        private void five_Click(object sender, RoutedEventArgs e)
        {
            Total( Convert.ToString(5) );
        }
        private void six_Click(object sender, RoutedEventArgs e)
        {
            Total( Convert.ToString(6) );
        }
        private void seven_Click(object sender, RoutedEventArgs e)
        {
            Total( Convert.ToString(7) );
        }
        private void eight_Click(object sender, RoutedEventArgs e)
        {
            Total( Convert.ToString(8) );
        }
        private void nine_Click(object sender, RoutedEventArgs e)
        {
            Total( Convert.ToString(9) );
        }
        private void ten_Click(object sender, RoutedEventArgs e)
        {
            Total( Convert.ToString(10) );
        }
        private void zero_Click(object sender, RoutedEventArgs e)
        {
            Total( Convert.ToString(0) );
        }

        private void add_Click(object sender, RoutedEventArgs e)
        {
            Total("+");
        }

        private void subtract_Click(object sender, RoutedEventArgs e)
        {
            Total("-");
        }

        private void multiply_Click(object sender, RoutedEventArgs e)
        {
            Total("*");
        }

        private void divide_Click(object sender, RoutedEventArgs e)
        {
            Total("/");
        }

        private void total_Click(object sender, RoutedEventArgs e)
        {
            int calculate;
            string content;

            content = Convert.ToString(lblTotal.Content);
            calculate = Convert.ToInt32(content);

        }

    }

}

因此，当用户单击总计按钮时，它应该打开 lblTotal.Content 并获取计算所需的数学并将 lblTotal.Content 设置为答案。

我收到此错误：

System.FormatException was unhandled
  _HResult=-2146233033
  _message=Input string was not in a correct format.
  HResult=-2146233033
  IsTransient=false
  Message=Input string was not in a correct format.
  Source=mscorlib
  StackTrace:
       at System.Number.StringToNumber(String str, NumberStyles options, NumberBuffer& number, NumberFormatInfo info, Boolean parseDecimal)
       at System.Number.ParseInt32(String s, NumberStyles style, NumberFormatInfo info)
       at System.String.System.IConvertible.ToInt32(IFormatProvider provider)
       at System.Convert.ToInt32(Object value)
       at Calculator.MainWindow.total_Click(Object sender, RoutedEventArgs e) in c:\Users\Administrator\Documents\Visual Studio 2013\Projects\Calculator\Calculator\MainWindow.xaml.cs:line 100
       at System.Windows.RoutedEventHandlerInfo.InvokeHandler(Object target, RoutedEventArgs routedEventArgs)
       at System.Windows.EventRoute.InvokeHandlersImpl(Object source, RoutedEventArgs args, Boolean reRaised)
       at System.Windows.UIElement.RaiseEventImpl(DependencyObject sender, RoutedEventArgs args)
       at System.Windows.UIElement.RaiseEvent(RoutedEventArgs e)
       at System.Windows.Controls.Primitives.ButtonBase.OnClick()
       at System.Windows.Controls.Button.OnClick()
       at System.Windows.Controls.Primitives.ButtonBase.OnMouseLeftButtonUp(MouseButtonEventArgs e)
       at System.Windows.UIElement.OnMouseLeftButtonUpThunk(Object sender, MouseButtonEventArgs e)
       at System.Windows.Input.MouseButtonEventArgs.InvokeEventHandler(Delegate genericHandler, Object genericTarget)
       at System.Windows.RoutedEventArgs.InvokeHandler(Delegate handler, Object target)
       at System.Windows.RoutedEventHandlerInfo.InvokeHandler(Object target, RoutedEventArgs routedEventArgs)
       at System.Windows.EventRoute.InvokeHandlersImpl(Object source, RoutedEventArgs args, Boolean reRaised)
       at System.Windows.UIElement.ReRaiseEventAs(DependencyObject sender, RoutedEventArgs args, RoutedEvent newEvent)
       at System.Windows.UIElement.OnMouseUpThunk(Object sender, MouseButtonEventArgs e)
       at System.Windows.Input.MouseButtonEventArgs.InvokeEventHandler(Delegate genericHandler, Object genericTarget)
       at System.Windows.RoutedEventArgs.InvokeHandler(Delegate handler, Object target)
       at System.Windows.RoutedEventHandlerInfo.InvokeHandler(Object target, RoutedEventArgs routedEventArgs)
       at System.Windows.EventRoute.InvokeHandlersImpl(Object source, RoutedEventArgs args, Boolean reRaised)
       at System.Windows.UIElement.RaiseEventImpl(DependencyObject sender, RoutedEventArgs args)
       at System.Windows.UIElement.RaiseTrustedEvent(RoutedEventArgs args)
       at System.Windows.UIElement.RaiseEvent(RoutedEventArgs args, Boolean trusted)
       at System.Windows.Input.InputManager.ProcessStagingArea()
       at System.Windows.Input.InputManager.ProcessInput(InputEventArgs input)
       at System.Windows.Input.InputProviderSite.ReportInput(InputReport inputReport)
       at System.Windows.Interop.HwndMouseInputProvider.ReportInput(IntPtr hwnd, InputMode mode, Int32 timestamp, RawMouseActions actions, Int32 x, Int32 y, Int32 wheel)
       at System.Windows.Interop.HwndMouseInputProvider.FilterMessage(IntPtr hwnd, WindowMessage msg, IntPtr wParam, IntPtr lParam, Boolean& handled)
       at System.Windows.Interop.HwndSource.InputFilterMessage(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled)
       at MS.Win32.HwndWrapper.WndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled)
       at MS.Win32.HwndSubclass.DispatcherCallbackOperation(Object o)
       at System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Int32 numArgs)
       at MS.Internal.Threading.ExceptionFilterHelper.TryCatchWhen(Object source, Delegate method, Object args, Int32 numArgs, Delegate catchHandler)
       at System.Windows.Threading.Dispatcher.LegacyInvokeImpl(DispatcherPriority priority, TimeSpan timeout, Delegate method, Object args, Int32 numArgs)
       at MS.Win32.HwndSubclass.SubclassWndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam)
       at MS.Win32.UnsafeNativeMethods.DispatchMessage(MSG& msg)
       at System.Windows.Threading.Dispatcher.PushFrameImpl(DispatcherFrame frame)
       at System.Windows.Threading.Dispatcher.PushFrame(DispatcherFrame frame)
       at System.Windows.Threading.Dispatcher.Run()
       at System.Windows.Application.RunDispatcher(Object ignore)
       at System.Windows.Application.RunInternal(Window window)
       at System.Windows.Application.Run(Window window)
       at System.Windows.Application.Run()
       at Calculator.App.Main() in c:\Users\Administrator\Documents\Visual Studio 2013\Projects\Calculator\Calculator\obj\Debug\App.g.cs:line 0
       at System.AppDomain._nExecuteAssembly(RuntimeAssembly assembly, String[] args)
       at System.AppDomain.ExecuteAssembly(String assemblyFile, Evidence assemblySecurity, String[] args)
       at Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly()
       at System.Threading.ThreadHelper.ThreadStart_Context(Object state)
       at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
       at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
       at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
       at System.Threading.ThreadHelper.ThreadStart()
  InnerException: 

我希望有一个修复。当我点击总按钮时，程序崩溃，然后我得到上面的错误。

Answer 1

您正在尝试使用Convert.ToInt32 将2+5 转换为7。这不是Convert.ToInt32 所做的。 Convert.ToInt32 和 int.Parse 接受一个表示数字的字符串（12345 或 -1245）并将其转换为整数。

您可能应该先查看data types，然后再进行其他操作。

您需要自己解析表达式，或使用表达式解析器。见I need a fast runtime expression parser或How would you create an expression parser in c#?

有关如何在 WPF 中制作计算器的示例不解析表达式，请参阅 MSDN Sample calculator。

Answer 2

使用链接中给出的Int32.TryParse (MSDN)。

Answer 3

lblTotal.Content 可能是您的问题，因为它可能不是存储为字符串的数字，或者该字符串中可能有其他字符。

Answer 4

private void total_Click(object sender, RoutedEventArgs e)
{
    int content ;
    int.TryParse(convert.ToString(lblTotal.Content), out content );
    int calculate = content;
    lblTotal.Content =convert.ToString( calculate);
}

Answer 5

从这里的调用堆栈中， 在 System.Convert.ToInt32（对象值）。 似乎说您对 Convert.ToInt32 的输入类型不正确。我不确定您的 lblTotal.Content 类型，因为您没有在此处放置相关代码，但我想它可能不是字符串，您能看一下吗？我猜如果 lblTotal.Content 是一个容器，它应该使用 lblTotal.Content.Text 之类的东西

Answer 6

如何获取标签的 Content 属性。对于 Labell 内容属性在 win 表单中不存在。

如果它对你可用，则使用 ToString() 函数将字符串值分配给 Content。

private void total_Click(object sender, RoutedEventArgs e) {

lblTotal.Content=Convert.ToInt32(lblTotal.Content).ToString();

}

Answer 7

这应该会给你一个提示：输入字符串的格式不正确。

从 string 到 int 的转换失败了。使用 Int32.TryParse 或在您的代码中添加一些异常处理：

int calculate;
int content;

if (Int32.TryParse(lblTotal.Content, out content))
{
    calculate = content;
    lblTotal.Content = calculate.ToString();
}
else
{
    lblTotal.Content = String.Format("Error converting {0}", lblTotal.Content);
}

上面的代码在这方面完全没有做任何事情，顺便说一下，你取 lblTotal 的内容，将其转换为 int，分配给计算并将 lblTotal 的内容设置为相同的值。

Answer 8

这应该可行：

        int content;
        if (Int32.TryParse(lblTotal.Content.ToString(), out content))
        {
            int calculate = content;
            lblTotal.Content = calculate;
        }

如果条件是true，数值将被分配给content，然后你的方法的其余部分执行。

如果您不想在该标签内进行数学运算，那当然是这样。

编辑：

这里有一篇对你很有帮助的文章：

http://code.msdn.microsoft.com/windowsdesktop/Simple-Calculator-d1d8cf4c/view/SourceCode#content

点击Browse Code标签并浏览代码。