新手一个问题
[code=C#][/code]
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.IO;

namespace openfile
{
  public partial class Form1 : Form
  {
  public Form1()
  {
  InitializeComponent();
  }

  private void Form1_Load(object sender, EventArgs e)
  {

  }

  private void 保存ToolStripMenuItem_Click(object sender, EventArgs e)
  {

  if (openFileDialog1.FileName != "")
  {
  StreamWriter a = new StreamWriter(openFileDialog1.FileName);
  a.Write(richTextBox1.Text);
  a.Close();
  // openFileDialog1 = richTextBox1.Text;
  }
  else
  {
  // saveFileDialog1.Filter = "文本文件(*.txt)|*.txt|所有文件(*.*)|*.*";

   
  StreamWriter a = new StreamWriter(saveFileDialog1.FileName, true);
  a.WriteLine(richTextBox1.Text);
  a.Close();
  // richTextBox1.Text = string.Empty;
   
  }
  }
  private void saveFileDialog1_FileOk(object sender, CancelEventArgs e)
  {

  }

  private void 新建ToolStripMenuItem_Click(object sender, EventArgs e)
  {
  // public static CreateAccessibilityInstance();
  // richTextBox1.Text = string.Empty;
  // FileInfo crea = new FileInfo("D:\\1.txt");
  // crea.Create();
  richTextBox1.Text = "";
   
  }

  private void 打开ToolStripMenuItem_Click(object sender, EventArgs e)
  {
  openFileDialog1.Filter = "文本文件(*.txt)|*.txt|所有文件(*.*)|*.*";
  if (openFileDialog1.ShowDialog() == DialogResult.OK)
  {
  richTextBox1.Text = string.Empty;
  StreamReader b = new StreamReader(openFileDialog1.FileName);
  richTextBox1.Text = b.ReadToEnd();
  b.Close();
  }
  }

  private void 另存为ToolStripMenuItem_Click(object sender, EventArgs e)
  {
  if (richTextBox1.Text == string.Empty)
  {
  MessageBox.Show("不能输入为空");
  }
  else
  {
  saveFileDialog1.Filter = "文本文件(*.txt)|*.txt|所有文件(*.*)|*.*";
  }
  if (saveFileDialog1.ShowDialog() == DialogResult.OK)
  {
  StreamWriter a = new StreamWriter(saveFileDialog1.FileName, true);
  a.WriteLine(richTextBox1.Text);
  a.Close();
  // richTextBox1.Text = string.Empty;
  }
  }
  }
}
[code=C#][/code]

主要是“保存”功能我很疑惑 使用if (openFileDialog1.FileName != "")这个条件语句，“保存”功能正常使用

如果使用 if (openFileDialog1.ShowDialog() == DialogResult.OK)或者 if (saveFileDialog1.ShowDialog() == DialogResult.OK),功能就变成了“另存为”，无法