创建包含两个文本框和两个按钮的 Windows 应用程序

Question

当我试图输入黄色字体时，我搞砸了我的代码。请帮助!!

说明： 创建一个包含两个文本框和两个按钮的 Windows 应用程序。文本框应该用于允许用户输入两个正数值。这些按钮应标记为“添加”和“乘法”。创建事件处理程序方法来检索值、执行计算并在标签上显示计算结果。结果标签最初应设置为不可见，字体颜色为黄色。如果输入了无效数据，将结果标签上的字体颜色更改为红色并显示消息“值必须是数字且 >0”。显示最终答案时，字体颜色应为黄色。文本框标题需要额外的标签。不允许输入非数字字符。调用 TryParse() 方法来检索值。程序语句中涉及的所有控件都应命名。右对齐文本框中的值。

这是我在 form1 页面上得到的内容

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

        private void button1_Click(object sender, EventArgs e)
        {
            int val1;
            int val2;
            val1 = Convert.ToInt32(textBox1.Text);
            val2 = Convert.ToInt32(textBox2.Text);
            label3.Text = Convert.ToString(val1 + val2); //after this line I tried putting the code to give me yellow color text and now I have so many errors:(
        }

        private void button2_Click(object sender, EventArgs e)
        {
            int val1;
            int val2;
            val1 = Convert.ToInt32(textBox1.Text);
            val2 = Convert.ToInt32(textBox2.Text);
            label3.Text = Convert.ToString(val1 * val2);
        }

        private void Form1_Load(object sender, EventArgs e)
        {

        }
    }
}

有好心人可以帮帮我吗？我不太擅长这个。 谢谢

有人告诉我要这样修。

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

        private void button1_Click(object sender, EventArgs e)
        {
            int val1;
            int val2;
            if(!int.TryParse(textBox1.Text.Trim(), out val1))
            {
                lblYellow.ForeColor = Color.Yellow;
                lblYellow.Visible = true;
                lblYellow.Text = "First value is invalid";
                return;
            }
            if(!int.TryParse(textBox2.Text.Trim(), out val2))
            {
                lblYellow.ForeColor = Color.Yellow;
                lblYellow.Visible = true;
                lblYellow.Text = "Second value is invalid";
                return;
            }
            lblYellow.Visible = false;
            label3.Text = Convert.ToString(val1 + val2);

        }

        private void button2_Click(object sender, EventArgs e)
        {
            int val1;
            int val2;
            if(!int.TryParse(textBox1.Text.Trim(), out val1))
            {
                lblYellow.ForeColor = Color.Yellow;
                lblYellow.Visible = true;
                lblYellow.Text = "First value is invalid";
                return;
            }
            if(!int.TryParse(textBox2.Text.Trim(), out val2))
            {
                lblYellow.ForeColor = Color.Yellow;
                lblYellow.Visible = true;
                lblYellow.Text = "Second value is invalid";
                return;
            }
            lblYellow.Visible = false;
            label3.Text = Convert.ToString(val1 * val2);


        }

        private void Form1_Load(object sender, EventArgs e)
        {

        }
    }
}

但是我收到错误消息“当前上下文 Form1.cs 中不存在名称‘lblYellow’”我应该在 private void button1_click 行之前声明它吗？

Answer 1

你有什么错误？，我认为你必须在行后删除一个}：

label3.Text = Convert.ToString(val1 + val2);

Answer 2

label3.ForeColor = Color.Yellow;

...应该将标签颜色更改为黄色...

但是你还有一个问题。您不是在检查无效输入以将标签更改为红色，也不是在调用

TryParse

作为指令命令。

此外，说明指出用户应该能够输入任何正数值。这将包括8.9和216.75。我想如果你想要最好的成绩，你需要考虑到这一点。看看C#内置数据类型。

Answer 3

看起来您正在定义一个没有类或在类外的方法，请检查所有方法是否都在 Form1 内，并检查是否有额外或缺少的括号。

Answer 4

如果有人对此项目有疑问，那么这是最终产品。运行后看起来很不错。

一切都很好，应该如何！

---

{ 公共部分类 Form1：表单 { 公共 Form1() { 初始化组件(); }

    private void button1_Click(object sender, EventArgs e)
    {
        int val1;
        int val2;
        int valid1 = 0;
        int valid2 = 0;
        if(int.TryParse(textBox1.Text.Trim(), out val1))
        {
            if(val1>0)
            {
                valid1 = 1;
                caption1.ForeColor = Color.Yellow;
                caption1.Visible = true;
                caption1.Text = "First value is valid"; 
            }
            else
            {
                caption1.ForeColor = Color.Red;
                caption1.Visible = true;
                caption1.Text = "Value must be Greater than 0";
            }
        }
        else
        {
            caption1.ForeColor = Color.Red;
            caption1.Visible = true;
            caption1.Text = "Value must be Numeric";
        }
        if(int.TryParse(textBox2.Text.Trim(), out val2))
        {
            if (val2 > 0)
            {
                valid2 = 1;
                caption2.ForeColor = Color.Yellow;
                caption2.Visible = true;
                caption2.Text = "First value is valid";
            }
            else
            {
                caption2.ForeColor = Color.Red;
                caption2.Visible = true;
                caption2.Text = "Value must be Greater than 0";
            }
        }
        else
        {
            caption2.ForeColor = Color.Red;
            caption2.Visible = true;
            caption2.Text = "Value must be Numeric";
        }
        if((valid1 > 0)&& (valid2 > 0))
        {
            label3.Visible = true;
            label3.ForeColor = Color.Yellow;
            label3.Text = Convert.ToString(val1 + val2);
        }
        else
        {
            label3.Visible = false;
        }
    }

    private void button2_Click(object sender, EventArgs e)
    {
        int val1;
        int val2;
        int valid1 = 0;
        int valid2 = 0;
        if(int.TryParse(textBox1.Text.Trim(), out val1))
        {
            if (val1 > 0)
            {
                valid1 = 1;
                caption1.ForeColor = Color.Yellow;
                caption1.Visible = true;
                caption1.Text = "First value is valid";
            }
            else
            {
                caption1.ForeColor = Color.Red;
                caption1.Visible = true;
                caption1.Text = "Value must be Greater than 0";
            }
        }
        else
        {
            caption1.ForeColor = Color.Red;
            caption1.Visible = true;
            caption1.Text = "Value must be Numeric";
        }
        if(int.TryParse(textBox2.Text.Trim(), out val2))
        {
            if (val2 > 0)
            {
                valid2 = 1;
                caption2.ForeColor = Color.Yellow;
                caption2.Visible = true;
                caption2.Text = "First value is valid";
            }
            else
            {
                caption2.ForeColor = Color.Red;
                caption2.Visible = true;
                caption2.Text = "Value must be Greater than 0";
            }
        }
        else
        {
            caption2.ForeColor = Color.Red;
            caption2.Visible = true;
            caption2.Text = "Value must be Numeric";

        }
        if ((valid1 > 0) && (valid2 > 0))
        {
            label3.Visible = true;
            label3.ForeColor = Color.Yellow;
            label3.Text = Convert.ToString(val1 * val2);
        }
        else 
        {
            label3.Visible = false;
        }
         }

    private void Form1_Load(object sender, EventArgs e)
    {

    }

    private void textBox1_TextChanged(object sender, EventArgs e)
    {

    }
}

}

Answer 5

我知道这是两年后的事了，但我想人们仍然可能会为此寻求帮助。

private void btnAdd_Click(object sender, EventArgs e)
{
    int firstNumber, secondNumber;

    if (!int.TryParse(txtBxFirstNumber.Text, out firstNumber) || firstNumber < 1)
    {
        lblResults.Text = "First number needs\n to be numeric and > 0";
        lblResults.ForeColor = Color.Red;
        lblResults.Visible = true;
        txtBxFirstNumber.Clear();
        return;
    }
    if (!int.TryParse(txtBxSecondNumber.Text, out secondNumber) || secondNumber < 1)
    {
        lblResults.Text = "Second number need\n to be numeric and > 0";
        lblResults.ForeColor = Color.Red;
        lblResults.Visible = true;
        txtBxSecondNumber.Clear();
        return;
    }
    lblResults.ForeColor = Color.Yellow;
    lblResults.Visible = true;
    lblResults.Text = Convert.ToString(firstNumber + secondNumber);
}

private void btnMultiply_Click(object sender, EventArgs e)
{
    int firstNumber, secondNumber;

    if (!int.TryParse(txtBxFirstNumber.Text, out firstNumber) || firstNumber < 1)
    {
        lblResults.Text = "First number needs\n to be numeric";
        lblResults.ForeColor = Color.Red;
        lblResults.Visible = true;
        txtBxFirstNumber.Clear();
        return;
    }
    if (!int.TryParse(txtBxSecondNumber.Text, out secondNumber) && secondNumber < 1)
    {
        lblResults.Text = "Second number need\n to be numeric";
        lblResults.ForeColor = Color.Red;
        lblResults.Visible = true;
        txtBxSecondNumber.Clear();
        return;
    }
    lblResults.ForeColor = Color.Yellow;
    lblResults.Visible = true;
    lblResults.Text = Convert.ToString(firstNumber * secondNumber);
}

Answer 6

you should change the design name of that label to "lblYellow" then will work... 转到该标签的属性并向下滚动，有一个名为设计的部分，在那里你会发现“（名称）”将默认名称更改为“lblYellow”...