在线主题。老师给了我们这个,但是没有运行。在fileWriter.WriteLine为48的行上引发错误 System.NullReferenceException:'对象引用未设置为对象的实例。'
在线教程看起来完全不同
public partial class frmMain : Form
{
private StreamWriter fileWriter;
public class Record
{
public string Name { get; set; }
public string ID { get; set; }
public string Suburb { get; set; }
public decimal Fee { get; set; }
}
string fileName = "student.txt";
private void frmMain_Load(object sender, EventArgs e)
{
FileStream output = new FileStream(fileName,
FileMode.OpenOrCreate, FileAccess.Write);
fileWriter = new StreamWriter(output);
}
private void btnSave_Click(object sender, EventArgs e)
{
Record record = new Record();
record.Name = txtName.Text;
record.ID = txtID.Text;
record.Suburb = txtSuburb.Text;
record.Fee = Convert.ToDecimal(txtFee.Text);
fileWriter.WriteLine(record.Name + "," + record.ID + "," +
record.Suburb + "," + record.Fee); // Error here
txtName.Text = "";
txtID.Text = "";
txtSuburb.Text = "";
txtFee.Text = "";
}
}