乘法表文本框设置错误
本文关键字：设置 错误 文本 | 更新日期: 2023-09-27 18:11:01
我用c#编写了一个乘法表程序供学生学习。这是我今晚要完成的一个班级项目。
问题是，当我按下"检查答案"按钮时，抛出错误"输入字符串格式不正确"。
这是我的代码;这太啰嗦了。当检查文本框中的答案是否正确时，将抛出该错误。我还没有找到解决办法。如果你有什么建议或解决办法，请告诉我。
一份感激。克莱顿
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
public partial class ContentPages_MySecondCalculator : System.Web.UI.Page
{
int SelectedNum = 0;
protected void Page_Load(object sender, EventArgs e)
{
}
protected void btnTimesTable_Click(object sender, EventArgs e)
{
/*protects against incorrect input **/
int SelectedNum = 0;
switch (drpNumberList.SelectedValue)
{
case "1":
SelectedNum = 1;
break;
case "2":
SelectedNum = 2;
break;
case "3":
SelectedNum = 3;
break;
case "4":
SelectedNum = 4;
break;
case "5":
SelectedNum = 5;
break;
case "6":
SelectedNum = 6;
break;
case "7":
SelectedNum = 7;
break;
case "8":
SelectedNum = 8;
break;
case "9":
SelectedNum = 9;
break;
case "10":
SelectedNum = 10;
break;
case "11":
SelectedNum = 11;
break;
case "12":
SelectedNum = 12;
break;
}
/* the first list of numbers are set to their values here **/
lbl1.Text = SelectedNum.ToString();
lbl1b.Text = SelectedNum.ToString();
lbl1c.Text = SelectedNum.ToString();
lbl1d.Text = SelectedNum.ToString();
lbl1e.Text = SelectedNum.ToString();
lbl1f.Text = SelectedNum.ToString();
lbl1g.Text = SelectedNum.ToString();
lbl1h.Text = SelectedNum.ToString();
lbl1i.Text = SelectedNum.ToString();
lbl1j.Text = SelectedNum.ToString();
lbl1k.Text = SelectedNum.ToString();
lbl1l.Text = SelectedNum.ToString();
/* the second list of numbers that appears are set to their values here **/
lbl2a.Text = "1";
lbl2b.Text = "2";
lbl2c.Text = "3";
lbl2d.Text = "4";
lbl2e.Text = "5";
lbl2f.Text = "6";
lbl2g.Text = "7";
lbl2h.Text = "8";
lbl2i.Text = "9";
lbl2j.Text = "10";
lbl2k.Text = "11";
lbl2l.Text = "12";
}
// in case no input was taken
protected void lblNumberList_SelectedIndexChanged(object sender, EventArgs e)
{
}
/*
protected void txtBox1_TextChanged(object sender, EventArgs e)
{
}
* */
protected void btnCheckAnswers_Click(object sender, EventArgs e)
{
if (true)
{
lblFeedback1.Text = "correct";
}
else
{
lblFeedback1.Text = "incorrect";
}
if (true)
{
lblFeedback2.Text = "correct";
}
else
{
lblFeedback2.Text = "incorrect";
}
if (true)
{
lblFeedback3.Text = "correct";
}
else
{
lblFeedback3.Text = "incorrect";
}
if (true)
{
lblFeedback4.Text = "correct";
}
else
{
lblFeedback4.Text = "incorrect";
}
if (true)
{
lblFeedback5.Text = "correct";
}
else
{
lblFeedback5.Text = "incorrect";
}
if (true)
{
lblFeedback6.Text = "correct";
}
else
{
lblFeedback6.Text = "incorrect";
}
if (true)
{
lblFeedback7.Text = "correct";
}
else
{
lblFeedback7.Text = "incorrect";
}
if (true)
{
lblFeedback8.Text = "correct";
}
else
{
lblFeedback8.Text = "incorrect";
}
if (true)
{
lblFeedback9.Text = "correct";
}
else
{
lblFeedback9.Text = "incorrect";
}
if (true)
{
lblFeedback10.Text = "correct";
}
else
{
lblFeedback10.Text = "incorrect";
}
if (true)
{
lblFeedback11.Text = "correct";
}
else
{
lblFeedback11.Text = "incorrect";
}
if (true)
{
lblFeedback12.Text = "correct";
}
else
{
lblFeedback12.Text = "incorrect";
}
/*
if ((Convert.ToInt32(txtBox1.ToString())) == SelectedNum)
{
}
if ((Convert.ToInt32(txtBox2.ToString())) == SelectedNum * 2)
{
}
if ((Convert.ToInt32(txtBox2.ToString())) == SelectedNum * 3)
{
}
if ((Convert.ToInt32(txtBox2.ToString())) == SelectedNum * 4)
{
}
if ((Convert.ToInt32(txtBox2.ToString())) == SelectedNum * 5)
{
}
if ((Convert.ToInt32(txtBox2.ToString())) == SelectedNum * 6)
{
}
if ((Convert.ToInt32(txtBox2.ToString())) == SelectedNum * 7)
{
}
if ((Convert.ToInt32(txtBox2.ToString())) == SelectedNum * 8)
{
}
if ((Convert.ToInt32(txtBox2.ToString())) == SelectedNum * 9)
{
}
if ((Convert.ToInt32(txtBox2.ToString())) == SelectedNum * 10)
{
}
if ((Convert.ToInt32(txtBox2.ToString())) == SelectedNum * 11)
{
}
if ((Convert.ToInt32(txtBox2.ToString())) == SelectedNum * 12)
{
}
* */
}
}
当您尝试将无效字符串转换为int时，您将获得错误。例句:
Convert.ToInt32("asdf");
将抛出此错误，因为asdf无法转换为有效数字。以下代码不会抛出此错误:
Convert.ToInt32("123");
建议使用Int32。TryParse http://msdn.microsoft.com/en-us/library/f02979c7.aspx
这个函数是专门为防止抛出异常而引入的。下面是使用它的一个例子:
int number;
bool result = Int32.TryParse(value, out number);
if (result)
{
Console.WriteLine("Converted '{0}' to {1}.", value, number);
}
else
{
if (value == null) value = "";
Console.WriteLine("Attempted conversion of '{0}' failed.", value);
}