如何在我的 C# Windows 窗體中制作重置按鈕？

Question

我正在嘗試將重置按鈕設置為我的 C# Windows 窗體。 但是，當我用這樣的代碼清除文本框時：

        textBox1.Clear();
        textBox2.Clear();
        textBox3.Clear();
        textBox4.Clear();
        textBox5.Clear();
        textBox6.Clear();

然后，它給了我以下錯誤：“輸入字符串的格式不正確”

這是我的代碼：

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;
using System.Collections;

namespace MidTermPizzas
{
    public partial class Form1 : Form
    {
        pizzaOrder aOrder = new pizzaOrder();

        public Form1()
        {
            InitializeComponent();
        }

        private void formTitle_Click(object sender, EventArgs e)
        {

        }

        //click File, Exit
        private void exitToolStripMenuItem_Click(object sender, EventArgs e)
        {
            MessageBox.Show("Enjoy your pizza!");
            this.Close();
        }

        //click View, Summary of Orders Placed
        private void summaryOfOrdersToolStripMenuItem_Click(object sender, EventArgs e)
        {
            SummaryOfOrdersPlaced myForm = new SummaryOfOrdersPlaced();
            myForm.Show();
        }


        //amount of Pizzas label
        private void label1_Click(object sender, EventArgs e)
        {

        }

        //form load
        private void Form1_Load(object sender, EventArgs e)
        {

        }

        //sales tax label
        private void label3_Click(object sender, EventArgs e)
        {

        }

        //text in box to the right of "Amount of Pizzas"
        private void textBox1_TextChanged(object sender, EventArgs e)
        {
            aOrder.numberOfPizzas = int.Parse(textBox1.Text);
        }

        //text in box to the right of "Amount of Cokes"
        private void textBox2_TextChanged(object sender, EventArgs e)
        {
            aOrder.numberOfCokes = int.Parse(textBox2.Text);
        }

        //text in box to the right of "Sales Tax"
        private void textBox4_TextChanged(object sender, EventArgs e)
        {

        }

        //File Tool Strip Menu
        private void fileToolStripMenuItem_Click(object sender, EventArgs e)
        {

        }

        //amount of cokes label
        private void label2_Click(object sender, EventArgs e)
        {

        }

        //reset button
        private void button1_Click_1(object sender, EventArgs e)
        {
            //textBox1.Clear();
            //textBox2.Clear();
            //textBox3.Clear();
            //textBox4.Clear();
            //textBox5.Clear();
            //textBox6.Clear();
         }

        //text in box to the right of "Amount Due"
        private void textBox3_TextChanged_1(object sender, EventArgs e)
        {

        }

        //text in box to the right of "Amount Paid"
        private void textBox5_TextChanged(object sender, EventArgs e)
        {
            aOrder.getAmountPaid = double.Parse(textBox5.Text);
        }

        //click Calculate Change Due button
        private void calculateChangeDue_Click(object sender, EventArgs e)
        {
            textBox6.Text = Convert.ToString(aOrder.GetChangeDue());
        }

        //text in box to right of Change Due
        private void textBox6_TextChanged(object sender, EventArgs e)
        {

        }

        //amount due label
        private void label4_Click(object sender, EventArgs e)
        {

        }

        //amount paid label
        private void label5_Click(object sender, EventArgs e)
        {

        }

        //change due label
        private void label6_Click(object sender, EventArgs e)
        {

        }

        //click Calculate Amount Due
        private void calculateAmountDue_Click(object sender, EventArgs e)
        {
            textBox3.Text = Convert.ToString(aOrder.GetAmountDue());
        }

        //click Calculate Sales Tax
        private void button2_Click(object sender, EventArgs e)
        {
            textBox4.Text = Convert.ToString(aOrder.TaxDue());
        }


    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Collections;

namespace MidTermPizzas
{
    class pizzaOrder
    {
        public int numberOfCokes
        {
            get;

            set;
        }

        public int numberOfPizzas
        {
            get;

            set;
        }

        public double InputOrder()
        {
            const double COKE_PRICE = 1.49;
            const double PIZZA_PRICE = 7.99;
            double inputOrder = (numberOfCokes * COKE_PRICE) + (numberOfPizzas * PIZZA_PRICE);
            return inputOrder;
        }

        public double TaxDue()
        {
            const double TAX = .073;
            double taxDue = (this.InputOrder() * TAX);
            return taxDue;
        }

        public double GetAmountDue()
        {
            double getAmountDue = this.InputOrder() + this.TaxDue();
            return getAmountDue;
        }

        public double getAmountPaid
        { get; set; }

        public double GetChangeDue()
        {
            double getChangeDue = this.getAmountPaid - this.GetAmountDue();
            return getChangeDue;
        }
    }
}

Answer 1

private void textBox1_TextChanged(object sender, EventArgs e){
  aOrder.numberOfPizzas = textBox1.Text == "" ? 0 : int.Parse(textBox1.Text);
}

對其他文本框執行相同操作，您應該使用TryParse並為所有文本框使用 1 個TextChanged事件處理程序。

以下代碼使用TryParse並假設如果解析失敗，則默認值為0 ：

private void textBox1_TextChanged(object sender, EventArgs e){
  int v;
  if(int.TryParse(textBox1.Text, out v)){
    aOrder.numberOfPizzas = v;
  } else aOrder.numberOfPizzas = 0;
}

Answer 2

要么按照其他答案的建議使用 TryParse，要么在 clear 方法中為用於數字輸入的文本框放置 0。 另一種方法是將MaskedTextBox用於用於數字輸入的文本框。

Answer 3

在這里，您也可以使用手動方法。 在按鈕單擊函數中編寫以下代碼，

if (textBox1.Text != string.Empty || textBox2.Text != string.Empty || textBox3.Text != string.Empty || textBox4.Text != string.Empty || textBox5.Text != string.Empty || textBox6.Text != string.Empty)
            {
                textBox1.Text = "";
                textBox2.Text = "";
                textBox3.Text = "";
                textBox4.Text = "";
                textBox5.Text = "";
                textBox6.Text = "";
            }