c# - 使用 C# 进行输入验证和异常

Question

我正在尝试验证输入并处理该程序中的异常。验证以下内容:txtNAME 中的字符串不应留空，txtTELEPHONE 中的电话号码应至少为 10 位数字，txtEMAIL 应采用电子邮件格式，并带有“@”和“.”。如何验证这些输入并在输入错误的情况下处理异常？

public partial class Form1 : Form
{
    static int maxCount = 10;

    int[] employeeID = new int[maxCount];
    string[] employeeName = new string[maxCount];
    string[] jobTitle = new string[maxCount];
    string[] address = new string[maxCount];
    int[] telephoneNumber = new int[maxCount];
    string[] email = new string[maxCount];

    int addCount = 0;

    string fn = "employees.xml";

    int currentRec;

    private void btnADD_Click(object sender, EventArgs e)
    {
        employeeID[addCount] = Convert.ToInt32(txtEI.Text);
        employeeName[addCount] = txtNAME.Text;
        jobTitle[addCount] = txtJOB.Text;
        address[addCount] = txtADDRESS.Text;
        telephoneNumber[addCount] = Convert.ToInt32(txtTELEPHONE.Text);
        email[addCount] = txtEMAIL.Text;
        addCount++;
    }

    private void btnSAVE_Click(object sender, EventArgs e)
    {
      XmlTextWriter w = new XmlTextWriter(fn, Encoding.UTF8);
      w.Formatting = Formatting.Indented;
      w.WriteStartDocument();
      w.WriteStartElement("employees");
      for (int i = 0; i < addCount; i++)
      {
          w.WriteStartElement("employees");

          w.WriteElementString("employeeID", employeeID[i].ToString());
          w.WriteElementString("employeeName", employeeName[i]);
          w.WriteElementString("jobTitle", jobTitle[i]);
          w.WriteElementString("address", address[i]);
          w.WriteElementString("telephoneNumber", telephoneNumber[i].ToString());
          w.WriteElementString("email", email[i]);
          w.WriteEndElement();
      } w.WriteEndElement();
      w.WriteEndDocument();
      w.Close();
      Application.Exit();

    }

    private void Form1_Load(object sender, EventArgs e)
    {
        if (File.Exists(fn))
        {
            XmlTextReader r = new XmlTextReader(fn);
            r.WhitespaceHandling = WhitespaceHandling.None;
            while (r.Name != "employees")
                r.Read();
            while (r.Name == "employees")
            {
                r.ReadStartElement("employees");
                employeeID[addCount] = Convert.ToInt32(r.ReadElementString("employeeID"));
                employeeName[addCount] = r.ReadElementString("employeeName");
                jobTitle[addCount] = r.ReadElementString("jobTitle");
                address[addCount] = r.ReadElementString("address");
                telephoneNumber[addCount] = Convert.ToInt32(r.ReadElementString("telephoneNumber"));
                email[addCount] = r.ReadElementString("email");
                r.ReadEndElement();
                addCount++;

            } r.Close();
            DisplayRec();
        }
    }

    private void DisplayRec()
    {
        txtEI.Text = employeeID[currentRec].ToString();
        txtNAME.Text = employeeName[currentRec];
        txtJOB.Text = jobTitle[currentRec];
        txtADDRESS.Text = address[currentRec];
        txtTELEPHONE.Text = telephoneNumber[currentRec].ToString();
        txtEMAIL.Text = email[currentRec];
        lblRECORD.Text = (currentRec + 1).ToString() + "/" + addCount.ToString();

    }

    private void btnBACK_Click(object sender, EventArgs e)
    {
        if (currentRec > 0)
            currentRec--;
        DisplayRec();
    }

    private void btnNEXT_Click(object sender, EventArgs e)
    {
        if (currentRec < addCount - 1)
            currentRec++;
        DisplayRec();
    }

    private void btnCLEAR_Click(object sender, EventArgs e)
    {
        txtEI.Clear();
        txtNAME.Clear();
        txtJOB.Clear();
        txtADDRESS.Clear();
        txtTELEPHONE.Clear();
        txtEMAIL.Clear();

    }
}

Answer 1

1. txtNAME should not be left blank,

要识别名称是否为空、空或空白，您可以使用 String.IsNullOrWhiteSpace()方法。

来自 MSDN:String.IsNullOrWhiteSpace()

Indicates whether a specified string is null, empty, or consists only of white-space characters.

试试这个:

if(!String.IsNullOrWhiteSpace(txtNAME.Text))
{    
  //continue    
}
else
{
 MessageBox.Show("Error");    
}

2. txtTELEPHONE should be at least 10 digits,

您可以使用字符串的Length属性来识别电话号码是否有10位数字。

试试这个:

if(txtTELEPHONE.Text.Length>=10)
{    
  //continue    
}
else
{    
MessageBox.Show("Error");    
}

3. txtEMAIL should be in email format with "@" and "."

为了验证 EmailID，我建议您使用 RegEx 而不是仅检查 @ 和 . 字符。

试试这个:正则表达式

  Regex regex = new Regex(@"^([\w\.\-]+)@([\w\-]+)((\.(\w){2,3})+)$");
  Match match = regex.Match(txtEMAIL.Text);
  if (match.Success)
  {    
    //continue    
  }
  else
  {    
    MessageBox.Show("Error");    
  }

尝试一下:如果您只想检查 @ 和 . 字符

if(txtEMAIL.Text.Contains("@") && txtEMAIL.Text.Contains(".") )
{    
  //continue    
}
else
{    
MessageBox.Show("Error");    
}