c#中的keydown由于某种原因不起作用

Posted 2023-02-23

【中文标题】c#中的keydown由于某种原因不起作用

【英文标题】：keydown in c# doesn't work for some reason

【发布时间】：2012-01-28 11:13:51

【问题描述】：

我正在尝试做一个计算器，我所要做的就是让它与键盘一起工作。这应该有效，但它没有。

    private void Form1_KeyDown(object sender, KeyEventArgs e)
    
        if (e.KeyCode == Keys.D1)
        
            resultarea.Text = "fgdgd";
            //number(1);

        
    ....
    

知道可能出了什么问题吗？

编辑：它仍然无法正常工作。我想我不妨把整个代码贴出来。

public partial class Form1 : Form

    public Form1()
    
        InitializeComponent();
        KeyPreview = true;

    
    double first = 0;
    double second = 0;
    string op = "";
    bool last = true;

    public void calculate()
    
        double aux = first;
        first = second;

        if (op == "+")
            second = aux + second;
        else if (op == "-")
            second = aux - second;
        else if (op == "*")
            second = aux * second;
        else if (op == "/")
            if (second == 0)
                 first = aux; viewarea.Text = "Cannot divide by zero"; 
            else
                second = aux / second;
        //if (viewarea.Text == "Cannot divide by zero")
            resultarea.Text = second.ToString();

    

    public void number(int digit)
    
        if (last == true)
        
            resultarea.Clear();
            last = false;
            first = second;
            second = 0;
        
        resultarea.Text += digit.ToString();
        second = second * 10 + digit;

    

    public void sign(string sign)
    
        if (last==false && (first != 0 && second != 0))
            calculate();
        op = sign;
        debug.Text = op;
        last = true;
    

    private void equal_Click(object sender, EventArgs e)
    
        if (last == false && (first != 0 && second !=0 ))
            calculate();
        op = "";
        last = true;
    

    private void one_Click(object sender, EventArgs e)
    
        number(1);
    

    private void two_Click(object sender, EventArgs e)
    
        number(2);
    

    private void plus_Click(object sender, EventArgs e)
    
        sign("+");
    

    private void minus_Click(object sender, EventArgs e)
    
        sign("-");
    



    private void three_Click(object sender, EventArgs e)
    
        number(3);
    

    private void creset_Click(object sender, EventArgs e)
    
        first = 0;
        second = 0;
        op = "";
        last = true;
        viewarea.Text = "";
        resultarea.Text = "";
        debug.Text = "";
    

    private void four_Click(object sender, EventArgs e)
    
        number(4);
    

    private void five_Click(object sender, EventArgs e)
    
        number(5);
    

    private void six_Click(object sender, EventArgs e)
    
        number(6);
    

    private void seven_Click(object sender, EventArgs e)
    
        number(7);
    

    private void eight_Click(object sender, EventArgs e)
    
        number(8);
    

    private void nine_Click(object sender, EventArgs e)
    
        number(9);
    

    private void zero_Click(object sender, EventArgs e)
    
        number(0);
    

    private void divide_Click(object sender, EventArgs e)
    
        sign("/");
    

    private void times_Click(object sender, EventArgs e)
    
        sign("*");
    

    private void sqr_Click(object sender, EventArgs e)
    
        second = Math.Sqrt(second);
        resultarea.Text = second.ToString();
    

    private void cos_Click(object sender, EventArgs e)
    
        second = Math.Cos(second);
        resultarea.Text = second.ToString();
    

    private void sin_Click(object sender, EventArgs e)
    
        second = Math.Sin(second);
        resultarea.Text = second.ToString();
    

    private void tan_Click(object sender, EventArgs e)
    
        second = Math.Tan(second);
        resultarea.Text = second.ToString();
    

    private void nfac_Click(object sender, EventArgs e)
    
        double aux = second;
        if (second == 0)
            aux = 1;
        else
        for (double i = 1; i < second; i++)
            aux= aux*i;
        second = aux;
        resultarea.Text = second.ToString();
    

    private void log_Click(object sender, EventArgs e)
    
        second = Math.Log(second);
        resultarea.Text = second.ToString();
    

    private void ln_Click(object sender, EventArgs e)
    
        second = Math.Log10(second);
        resultarea.Text = second.ToString();
    

    private void xexp_Click(object sender, EventArgs e)
    
        second = Math.Pow(second ,2);
        resultarea.Text = second.ToString();
    

    private void dot_Click(object sender, EventArgs e)
    

    

    private void Form1_KeyDown(object sender, KeyEventArgs e)
    
        if (e.KeyCode == Keys.D1 || e.KeyCode == Keys.NumPad1)
        
            viewarea.Text = "fgdgd";
            //number(1);


        
        else if (e.KeyCode == Keys.D2 || e.KeyCode == Keys.NumPad2)
        
            number(2);
        
        else if (e.KeyCode == Keys.D3 || e.KeyCode == Keys.NumPad3)
        
            number(3);
        
        else if (e.KeyCode == Keys.D4 || e.KeyCode == Keys.NumPad4)
        
            number(4);
        
        else if (e.KeyCode == Keys.D5 || e.KeyCode == Keys.NumPad5)
        
            number(5);
        
        else if (e.KeyCode == Keys.D6 || e.KeyCode == Keys.NumPad6)
        
            number(6);
        
        else if (e.KeyCode == Keys.D7 || e.KeyCode == Keys.NumPad7)
        
            number(7);
        
        else if (e.KeyCode == Keys.D8 || e.KeyCode == Keys.NumPad8)
        
            number(8);
        
        else if (e.KeyCode == Keys.D9 || e.KeyCode == Keys.NumPad9)
        
            number(9);
        
        else if (e.KeyCode == Keys.Divide)
        
            sign("/");
        
        else if (e.KeyCode == Keys.Subtract)
        
            sign("-");
        
        else if (e.KeyCode == Keys.Add)
        
            sign("+");
        
        else if (e.KeyCode == Keys.Enter)
        
            sign("=");
        
    
    private void Form1_Load(object sender, EventArgs e)
    

    

【问题讨论】：

是 Winforms 还是 Wpf？您在表单上是否有其他控件，谁可能拥有焦点？

@Fischer，我们可以通过 KeyEventArgs 看到，它是 Windows 窗体。

对不起，是的。当我按 1 时，resultarea 文本框里面没有文本

当我按下任何键时什么都没有发生，除了按下所选按钮的空格 lol

【参考方案1】：

假设您有一个 WinForms 项目，请将表单的 KeyPreview 属性设置为 true，就像这样（例如在构造函数中）：

public Form1()

    InitializeComponent();
    KeyPreview = true;

它应该像你预期的那样工作。

编辑：由于您的评论，我添加了代码以捕获所有标志（将其添加到您的 Form1_KeyDown 方法中）

if (((e.KeyCode == Keys.D7) && (e.Modifiers == Keys.Shift)) || (e.KeyCode == Keys.Divide))

    sign("/");

else if (((e.KeyCode == Keys.Oemplus) && (e.Modifiers == Keys.Shift)) || (e.KeyCode == Keys.Multiply))

    sign("*");

else if ((e.KeyCode == Keys.OemMinus) || (e.KeyCode == Keys.Subtract))

    sign("-");
 
else if ((e.KeyCode == Keys.Oemplus) || (e.KeyCode == Keys.Add))

    sign("+");
 
else if (e.KeyCode == Keys.Enter)

    sign("=");

【讨论】：

朋友，我看到了你的答案，我喜欢你自信地添加的方式它应该像你预期的那样工作 +1 :-)

@PankajUpadhyay：谢谢！ :-D

@AndreiCristianProdan：Form1_KeyDown 方法是否在某些情况下被触发？是不是还在连线。除非我可以在您的示例代码中看到该事件的订阅，否则我猜它是在设计器中连接的。也许这迷路了？

天哪，我简直不敢相信。我忘记了。去形成事件并添加我的keydown事件方法。现在工作。它仍然需要 KeyPreview = true，为什么？

还有一件事。这些标志不像 Keys.Substract 等那样工作。知道为什么吗？