Question

我正在试图找出一个我应该根据我的书写的代码（首先进入C＃，3.5版）。我完全被一个我想写的循环所困惑。这就是我想要做的事情：

制作表格，按钮，复选框和标签。仅当标记了复选框时，按钮才会更改标签的背景颜色。按下按钮时，颜色可以在红色和蓝色之间切换。

这是我目前的代码。

namespace SecondColorChangingWindow
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            while (checkBox1.Checked == false) // The code will stop if the box isn't checked
            {
                MessageBox.Show("You need the check box checked first!");
                break;//Stops the infinite loop
            }
            while (checkBox1.Checked == true)// The code continues "if" the box is checked.
            {
                bool isRed = false; // Makes "isRed" true, since the background color is default to red.

                if (isRed == true) // If the back ground color is red, this will change it to blue
                {
                    label1.BackColor = Color.Blue; // changes the background color to blue
                    isRed = false; //Makes "isRed" false so that the next time a check is made, it skips this while loop
                    MessageBox.Show("The color is blue.");//Stops the program so I can see the color change
                }
                if (isRed == false)//if the back ground color is blue, this will change it to red
                {
                    label1.BackColor = Color.Red;//Makes the background color red
                    isRed = true;//Sets the "isRed" to true
                    MessageBox.Show("The color is red.");//Stops the program so I can see the color change.
                }
            }
        }
    }
}

现在它只在红色上循环。我不明白我做错了什么。这不是我写的第一个代码。我已经从整数到布尔试图让颜色改变，但它要么：使颜色一次，而不是其他颜色。或者程序冻结，因为它无限循环。

Answer 1

你不需要while循环，尝试条件并检查标签颜色如下

   private void button1_Click(object sender, EventArgs e)
    {
        if(!checkBox1.Checked)
        {
            MessageBox.Show("You need the check box checked first!");
        }
        else
        {
            //changes the background color
            label1.BackColor = label1.BackColor == Color.Blue? Color.Red:Color.Blue;
            MessageBox.Show("The color is " + label1.BackColor.ToString());
        }
    }

如果checkBox1已选中，则在当前代码中

没有中断条件。它将运行无限循环并冻结程序。您最好在每个break;行之后添加MessageBox.Show。

Answer 2

您不需要两个while语句。您正在编写一个事件例程，该例程在每次单击button1时运行。只需设置属性或显示消息并返回调用此例程的“事件处理器”。

private void button1_Click(object sender, EventArgs e)
{
    if (checkBox1.Checked == false) // The code will stop if the box isn't checked
    {
        MessageBox.Show("You need the check box checked first!");
    }
    else //(checkBox1.Checked == true)
    { // etc.

大多数事件例程将执行一个函数，然后返回调用者。

Answer 3

你也可以这样做：

    private void button1_Click(object sender, EventArgs e)
    {
        if (checkBox1.Checked)
        {

            if (label1.BackColor == Color.Blue)
            {
                label1.BackColor = Color.Red;
                MessageBox.Show("The color is red.");
            }
            else
            {
                label1.BackColor = Color.Blue;
                MessageBox.Show("The color is blue.");
            }
        }
        else
        {
            MessageBox.Show("You need the check box checked first!");
        }
    }

C＃按钮循环？

3 个答案: