关于C#打印的问题！

Question

是按照C#经典教程（第三版）中做的例子。
 private void OnPrintPage(object sender, PrintPageEventArgs e)
        {            
            int x = e.MarginBounds.Left;
            int y = e.MarginBounds.Top;
            while( linesPrinted < lines.Length )//程序在运行到这里时出错。提示：未将对象引用到实例
            {
                e.Graphics.DrawString(lines[linesPrinted++] , new Font("Arial", 10), Brushes.Black, x, y);
                y += 15;
            
                if (y >= e.MarginBounds.Bottom)
                {
                    e.HasMorePages = true;
                    return;
                }
            }
            linesPrinted = 0;
            e.HasMorePages = false;        }        private void miFilePrint_Click(object sender, EventArgs e)
        {
            try
            {
                if (DlgPrint.ShowDialog() == DialogResult.OK)
                {
                      printDocument.Print();
                }
              
            }
            catch(InvalidPrinterException ex)
            {
                MessageBox.Show(this,ex.Message,"本页面",MessageBoxButtons.OK,MessageBoxIcon.Exclamation);
            }
        }
第一次在这里发布求助，不到之处请谅解！

Answer 1

查看一下是否对lines进行过初始化。

Answer 2

成员变量已经定义了。
 public partial class SimpleEditorForm : Form
    {
        private string filename = "Untitled";
        private string[] lines;
        private int linesPrinted;        public SimpleEditorForm(string filename)
        {
            InitializeComponent();
            if (filename != null)
            {
                this.filename = filename;
                OpenFile();
            }
        }
 private void OnBeginPrint(object sender, PrintEventArgs e)
        {
            char[] param ={ '\n' };
            string[] lines = TextBoxEdit.Text.Split(param);
            int i = 0;
            char[] trimParam ={ '\r' };
            foreach (string s in lines)
            {
                lines[i++] = s.TrimEnd(trimParam);
            }
        }

Answer 3

问题解决了
private   void   OnBeginPrint(object   sender,   PrintEventArgs   e) 
                { 
                        char[]   param   ={   '\n'   }; 
                        string[]   lines   =   TextBoxEdit.Text.Split(param); 
                        int   i   =   0; 
                        char[]   trimParam   ={   '\r'   }; 
                        foreach   (string   s   in   lines) 
                        { 
                                lines[i++]   =   s.TrimEnd(trimParam); 
                        } 
                }
多了一个string[] ，谢谢楼上。