Question

我有两个关于这个简单的计算器应用程序的快速问题，我试图用C＃构建。（顺便说一下不做作业）我试图让MessageBox.Show消息显示在我的代码的乘法和添加部分，但即使我输入负值，它们似乎也不会显示。该应用程序似乎只是做数学。此外，这可能是一个愚蠢的，如何删除应用程序中出现的label5文本，而不删除它在属性窗口中？

非常感谢任何帮助，谢谢！

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

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

    private void label1_Click(object sender, EventArgs e)
    {

    }

    private void txtFirstValue_TextChanged(object sender, EventArgs e)
    {

    }

    private void btnAdd_Click(object sender, EventArgs e)
    {
        double firstValue;
        double secondValue;
        double answer;

        while (double.TryParse(txtFirstValue.Text, out firstValue) == false)
        {
            MessageBox.Show("The value(s) entered must be > 0");
        }
        while(double.TryParse(txtSecondValue.Text, out secondValue) == false)
        {
            MessageBox.Show("The value(s) entered must be > 0");
        }


            answer = firstValue + secondValue; 
            lblAnswer.Text = answer.ToString();

    }

    private void btnMultiply_Click(object sender, EventArgs e)
    {
        double firstValue;
        double secondValue;
        double answer;

        while (double.TryParse(txtFirstValue.Text, out firstValue) == false)
        {
            MessageBox.Show("The value(s) entered must be > 0");
        }
        while (double.TryParse(txtSecondValue.Text, out secondValue) == false)
        {
            MessageBox.Show("The value(s) entered must be > 0");
        }


            answer = firstValue * secondValue; 
            lblAnswer.Text = answer.ToString();

    }

    private void lblAnswer_Click(object sender, EventArgs e)
    {
        lblAnswer.Text = ""; //tries to get rid of "label5" text in application, but fails to do so
    }
}

}

Answer 1

1）你应该将while更改为＆＃34; if＆＃34;：

private void btnAdd_Click（object sender，EventArgs e） { double firstValue; double secondValue; 双重答案;

    if (double.TryParse(txtFirstValue.Text, out firstValue) == false)
    {
        MessageBox.Show("The value(s) entered must be > 0");
    }
    if(double.TryParse(txtSecondValue.Text, out secondValue) == false)
    {
        MessageBox.Show("The value(s) entered must be > 0");
    }


        answer = firstValue + secondValue; 
        lblAnswer.Text = answer.ToString();

}

2）Ladel5在哪里？它似乎不存在......

Answer 2

您可以尝试以下代码来显示MessageBox，然后该值小于0：

if (n1 < 0 || n2 < 0)
                MessageBox.Show("Value less than ZERO ", "Value less than ZERO",MessageBoxButtons.OK , MessageBoxIcon.Exclamation);

至于摆脱标签，你可以尝试：

label5.Visible = false;

C＃中的简单计算器应用

2 个答案: