Question

我试图调试此代码，但在第三种方法中，它不允许我使用不同的数据类型。在我的教科书中，该示例显示了它们使用不同的数据类型作为参数。为什么不允许我这样做？我确定此代码还有其他问题，但我甚至无法调试它们，直到我清除错误。

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 WP_Week3_Problem2
{
    public partial class Problem2 : Form
    {
        public Problem2()
        {
            InitializeComponent();
        }

        int[] productID = { 1234, 5678, 5677, 8765, 2345, 8734 };
        double[] productPrice = { 5.55, 20.0, 40.0, 56.34, 78.10, 98.0 };
        String[] productName = { "Pencil", "Backpack", "MessengerBag", "RoomHeater", "SewingMachine", "Decorative Lamp" };

        private void Problem2_Load(object sender, EventArgs e)
        {

        }

        private void buttonLoadTable_Click(object sender, EventArgs e)
        {
            labelOutput.Text = "ProdID     Price        ProdName";
            for (int i = 0; i < productID.Length; i = i + 1)
            {
                labelOutput.Text += String.Format("\n {0}       {1}       {2} ", productID[i], productPrice[i].ToString("C"), productName[i]);
            }
        }

        private void buttonSearch_Click(object sender, EventArgs e)
        {
            int prodID = Convert.ToInt32(textBoxID.Text);
            String prodName = textBoxName.Text;
            double prodPrice = Convert.ToDouble(textBoxPrice.Text);
            SearchProducts(prodID);
            SearchProducts(prodName);
            SearchProducts(prodID, prodName, prodPrice);
        }
        private void SearchProducts(int prodID)
        {
            int prodMinus = prodID - 1;
            int idExists = Array.IndexOf(productID, prodMinus);
            if (idExists == -1)
            {
                labelOutput.Text = "That product ID is invalid.\nPlease enter a valid product ID";
                textBoxID.Text = "";
            }
        }
        private void SearchProducts(String prodName)
        {
            String nameExists = Array.IndexOf(productName, prodName).ToString();
            bool isName = true;
            if (nameExists == "Pencil")
                isName = true;
            else if (nameExists == "Backpack")
                isName = true;
            else if (nameExists == "MessengerBag")
                isName = true;
            else if (nameExists == "RoomHeater")
                isName = true;
            else if (nameExists == "SewingMachine")
                isName = true;
            else if (nameExists == "Decorative Lamp")
                isName = true;
            else
                isName = false;
            labelOutput.Text = "This Product Name is invalid.\nPlease enter a valid Product Name";
        }
        private void SearchProducts(String prodName, int prodID, double prodPrice)
        {
            labelOutput.Text = String.Format("Your Product ID of {0} is a {2} and it costs: {1}", prodID, prodName, prodPrice.ToString("C"));
        }
    }
}

Answer 1

更改此行

SearchProducts(prodID, prodName, prodPrice);

到这个

SearchProducts(prodName, prodID, prodPrice);

SearchProducts方法需要String，int和double参数，但是你传递了一个int，string和double。

Answer 2

您还可以对文本框转换中的某些错误处理进行有用的操作 - 从不是一个很好的计划来获取文本框并希望用户只需输入有效数据：

    private void buttonSearch_Click(object sender, EventArgs e)
    {

        bool process = true;
        String prodName = textBoxName.Text;
        int prodID;
        double prodPrice;
        try
        {
            prodID = Convert.ToInt32(textBoxID.Text);
        }
        catch(Exception ex)
        {
            MessageBox.Show(ex.Message, "Error in product ID", MessageBoxButtons.OK, MessageBoxIcon.Error);
            process = false;        
        }
        try
        {
            prodPrice = Convert.ToDouble(textBoxPrice.Text);
        }
        catch (Exception ex)
        {
            MessageBox.Show(ex.Message, "Error in product price", MessageBoxButtons.OK, MessageBoxIcon.Error);
            process = false;

        }
        if (process)
        {
            SearchProducts(prodID);
            SearchProducts(prodName);
            SearchProducts(prodID, prodName, prodPrice);
        }
    }

编辑：

我忘了说你可以用类解析器替换Convert，这样就不需要try / catch了：

if (!Int32.TryParse(textBoxID.Text, out prodID))
{
    process = false;
    // message method of choice to tell user of error
}

C＃Argument无法将int转换为字符串或将字符串转换为int

2 个答案: