采用新数字的计算器

Question

单击相等按钮或输入（键盘）后，我希望我的计算器取一个新数字，基本上好像TextBox中没有任何内容，即使答案仍然显示。

目前，所有号码都会保留，新号码会添加到最后。在计算之后，如果我点击一个数字按钮或小键盘（键盘），我希望它清除TextBox并添加新的数字。

例如，2 + 2 = 4，当我输入一个像5这样的新数字时，TextBox不会清除在单击等号或输入（键盘）后已经在TextBox中的数字（4），TextBox认为我想要它说45但我希望只要在点击等号或输入（键盘）后输入新号码就可以清除号码。

如果您不介意，您是否也会举例说明使用我的代码解决此问题您将采取的措施。

public partial class Form1 : Form
{
    Double value = 0;
    String operation = "";
    bool operation_pressed = false;
    public Form1()
    {
        InitializeComponent();
    }
    private void button_Click(object sender, EventArgs e)
    {
        if ((textBoxResult.Text == "0")||(operation_pressed))
            textBoxResult.Clear();
        operation_pressed = false;
        Button b = (Button)sender;
        if (b.Text == ".")
        {
            if (!textBoxResult.Text.Contains("."))
            textBoxResult.Text = textBoxResult.Text + b.Text;
        }
        else
                textBoxResult.Text = textBoxResult.Text + b.Text;
    }
    private void operator_Click(object sender, EventArgs e)
    {
        Button b = (Button)sender;
        if (value != 0)
        {
            buttonEqual.PerformClick();
            operation_pressed = true;
            operation = b.Text;
            labelEquation.Text = value + " " + operation;
        }
        else
        {
            operation = b.Text;
            value = Double.Parse(textBoxResult.Text);
            operation_pressed = true;
            labelEquation.Text = value + " " + operation;
        }
    }
    private void buttonEqual_Click(object sender, EventArgs e)
    {
        labelEquation.Text = "";
        switch(operation)
        {
            case "+":
                textBoxResult.Text = (value + Double.Parse(textBoxResult.Text)).ToString();
                break;
            case "-":
                textBoxResult.Text = (value - Double.Parse(textBoxResult.Text)).ToString();
                break;
            case "*":
                textBoxResult.Text = (value * Double.Parse(textBoxResult.Text)).ToString();
                break;
            case "/":
                textBoxResult.Text = (value / Double.Parse(textBoxResult.Text)).ToString();
                break;
            default:
                break;
        }
        value = Doudble.Parse(textBoxResult.Text);
        operation = "";
    }
    private void buttonClearEntry_Click(object sender, EventArgs e)
    {
        textBoxResult.Text = "0";
    }
    private void buttonClear_Click(object sender, EventArgs e)
    {
        textBoxResult.Text = "0";
        value = 0;
        labelEquation.Text = "";
    }
    private void keyboard_KeyPress(object sender, KeyPressEventArgs e)
    {
        switch (e.KeyChar.ToString())
        {
            case "0":
                buttonZero.PerformClick();
                break;
            case "1":
                buttonOne.PerformClick();
                break;
            case "2":
                buttonTwo.PerformClick();
                break;
            case "3":
                buttonThree.PerformClick();
                break;
            case "4":
                buttonFour.PerformClick();
                break;
            case "5":
                buttonFive.PerformClick();
                break;
            case "7":
                buttonSeven.PerformClick();
                break;
            case "8":
                buttonEight.PerformClick();
                break;
            case "9":
                buttonNine.PerformClick();
                break;
            case ".":
                buttonPeriod.PerformClick();
                break;
            case "+":
                buttonAddition.PerformClick();
                break;
            case "-":
                buttonMinus.PerformClick();
                break;
            case "*":
                buttonMultiply.PerformClick();
                break;
            case "/":
                buttonDivide.PerformClick();
                break;
            case "=":
                buttonEqual.PerformClick();
                break;
            default:
                break;
        }
    }
}