100165772.htm

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<p class=2 style='margin-left:21.45pt;FTEL:18.45pt'><span lang=EN-US>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
{</span></p>

<p class=2 style='margin-left:21.45pt;FTEL:18.45pt'><span lang=EN-US>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
chooseOpenFileDialog.ShowDialog();</span></p>

<p class=2 style='margin-left:21.45pt;FTEL:18.45pt'><span lang=EN-US>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
}</span></p>

<p class=2 style='margin-left:21.45pt;FTEL:18.45pt'><span lang=EN-US>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
void OnOpenFileDialogOK(object Sender, CancelEventArgs e)</span></p>

<p class=2 style='margin-left:21.45pt;FTEL:18.45pt'><span lang=EN-US>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
{</span></p>

<p class=2 style='margin-left:21.45pt;FTEL:18.45pt'><span lang=EN-US>&nbsp;
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;chosenFile =
chooseOpenFileDialog.FileName;</span></p>

<p class=2 style='margin-left:21.45pt;FTEL:18.45pt'><span lang=EN-US>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
this.Text = Path.GetFileName(chosenFile);</span></p>

<p class=2 style='margin-left:21.45pt;FTEL:18.45pt'><span lang=EN-US>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
DisplayFile();</span></p>

<p class=2 style='margin-top:0cm;margin-right:0cm;FTEL:8.15pt;
margin-left:21.45pt;FTEL:18.45pt'><span lang=EN-US>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
}</span></p>

<p class=MsoNormal><span style='font-family:宋体'>可以看出，用户单击</span><span
lang=EN-US>OK</span><span style='font-family:宋体'>，在文件对话框中选择一个文件后，就会调用方法</span><span
lang=EN-US>DisplayFile()</span><span style='font-family:宋体'>，该方法读取所选中的文件：</span></p>

<p class=2 style='margin-top:8.15pt;margin-right:0cm;FTEL:0cm;
margin-left:21.45pt;FTEL:.0001pt;FTEL:18.45pt'><span
lang=EN-US>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; void DisplayFile()</span></p>

<p class=2 style='margin-left:21.45pt;FTEL:18.45pt'><span lang=EN-US>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
{</span></p>

<p class=2 style='margin-left:21.45pt;FTEL:18.45pt'><span lang=EN-US>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
int nCols = 16;</span></p>

<p class=2 style='margin-left:21.45pt;FTEL:18.45pt'><span lang=EN-US>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
FileStream inStream = new FileStream(chosenFile, FileMode.Open, </span></p>

<p class=2 style='margin-left:21.45pt;FTEL:18.45pt'><span lang=EN-US>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
FileAccess.Read);</span></p>

<p class=2 style='margin-left:21.45pt;FTEL:18.45pt'><span lang=EN-US>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
long nBytesToRead = inStream.Length;</span></p>

<p class=2 style='margin-left:21.45pt;FTEL:18.45pt'><span lang=EN-US>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
if (nBytesToRead &gt; 65536/4) </span></p>

<p class=2 style='margin-left:21.45pt;FTEL:18.45pt'><span lang=EN-US>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
nBytesToRead = 65536/4;</span></p>

<p class=2 style='margin-left:21.45pt;FTEL:18.45pt'><span lang=EN-US>&nbsp;</span></p>

<p class=2 style='margin-left:21.45pt;FTEL:18.45pt'><span lang=EN-US>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
int nLines = (int)(nBytesToRead/nCols) + 1;</span></p>

<p class=2 style='margin-left:21.45pt;FTEL:18.45pt'><span lang=EN-US>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
string [] lines = new string[nLines];</span></p>

<p class=2 style='margin-left:21.45pt;FTEL:18.45pt'><span lang=EN-US>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
int nBytesRead = 0;</span></p>

<p class=2 style='margin-left:21.45pt;FTEL:18.45pt'><span lang=EN-US>&nbsp;</span></p>

<p class=2 style='margin-left:21.45pt;FTEL:18.45pt'><span lang=EN-US>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
for (int i=0 ; i&lt;nLines ; i++)</span></p>

<p class=2 style='margin-left:21.45pt;FTEL:18.45pt'><span lang=EN-US>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
{</span></p>

<p class=2 style='margin-left:21.45pt;FTEL:18.45pt'><span lang=EN-US>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
StringBuilder nextLine = new StringBuilder();</span></p>

<p class=2 style='margin-left:21.45pt;FTEL:18.45pt'><span lang=EN-US>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
nextLine.Capacity = 4*nCols;</span></p>

<p class=2 style='margin-left:21.45pt;FTEL:18.45pt'><span lang=EN-US>&nbsp;</span></p>

<p class=2 style='margin-left:21.45pt;FTEL:18.45pt'><span lang=EN-US>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
for (int j = 0 ; j&lt;nCols ; j++)</span></p>

<p class=2 style='margin-left:21.45pt;FTEL:18.45pt'><span lang=EN-US>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
{</span></p>

<p class=2 style='margin-left:21.45pt;FTEL:18.45pt'><span lang=EN-US>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
int nextByte = inStream.ReadByte();</span></p>

<p class=2 style='margin-left:21.45pt;FTEL:18.45pt'><span lang=EN-US>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
nBytesRead++;</span></p>

<p class=2 style='margin-left:21.45pt;FTEL:18.45pt'><span lang=EN-US>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
if (nextByte &lt; 0 || nBytesRead &gt; 65536)</span></p>

<p class=2 style='margin-left:21.45pt;FTEL:18.45pt'><span lang=EN-US>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
break;</span></p>

<p class=2 style='margin-left:21.45pt;FTEL:18.45pt'><span lang=EN-US>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
char nextChar = (char)nextByte;</span></p>

<p class=2 style='margin-left:21.45pt;FTEL:18.45pt'><span lang=EN-US>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
if (nextChar &lt; 16)</span></p>

<p class=2 style='margin-left:21.45pt;FTEL:18.45pt'><span lang=EN-US>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
nextLine.Append(&quot; x0&quot; + string.Format(&quot;{0,1:X}&quot;, </span></p>

<p class=2 style='margin-left:21.45pt;FTEL:18.45pt'><span lang=EN-US>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
(int)nextChar));</span></p>

<p class=2 style='margin-left:21.45pt;FTEL:18.45pt'><span lang=EN-US>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
else if </span></p>

<p class=2 style='margin-left:21.45pt;FTEL:18.45pt'><span lang=EN-US>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
(char.IsLetterOrDigit(nextChar) || </span></p>

<p class=2 style='margin-left:21.45pt;FTEL:18.45pt'><span lang=EN-US>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
char.IsPunctuation(nextChar))</span></p>

<p class=2 style='margin-left:21.45pt;FTEL:18.45pt'><span lang=EN-US>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
nextLine.Append(&quot;&nbsp; &quot; + nextChar + &quot; &quot;);</span></p>

<p class=2 style='margin-left:21.45pt;FTEL:18.45pt'><span lang=EN-US>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
else</span></p>

<p class=2 style='margin-left:21.45pt;FTEL:18.45pt'><span lang=EN-US>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
nextLine.Append(&quot; x&quot; + string.Format(&quot;{0,2:X}&quot;, </span></p>

<p class=2 style='margin-left:21.45pt;FTEL:18.45pt'><span lang=EN-US>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
(int)nextChar));</span></p>

<p class=2 style='margin-left:21.45pt;FTEL:18.45pt'><span lang=EN-US>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
}</span></p>

<p class=2 style='margin-left:21.45pt;FTEL:18.45pt'><span lang=EN-US>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
lines[i] = nextLine.ToString();</span></p>

<p class=2 style='margin-left:21.45pt;FTEL:18.45pt'><span lang=EN-US>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
}</span></p>

<p class=2 style='margin-left:21.45pt;FTEL:18.45pt'><span lang=EN-US>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
inStream.Close();</span></p>

<p class=2 style='margin-left:21.45pt;FTEL:18.45pt'><span lang=EN-US>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
this.textBoxContents.Lines = lines;</span></p>

<p class=2 style='margin-top:0cm;margin-right:0cm;FTEL:8.15pt;
margin-left:21.45pt;FTEL:18.45pt'><span lang=EN-US>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
}</span></p>

<p class=MsoNormal><span style='font-family:宋体'>在这个方法中进行了许多工作，首先为所选文件实例化一个</span><span lang=EN-US>FileStream</span><span style='font-family:宋体'>，指定要打开一个现有文件进行读取。然后确定要读取多少个字节，和显示多少行。这个字节数一般是文件中的字节数。文本框最多只能显示</span><span
lang=EN-US>65 536</span><span style='font-family:宋体'>个字符，但以我们选择的格式，文件中的每个字节可以显示</span><span
lang=EN-US>4</span><span style='font-family:宋体'>个字符，因此如果文件的字节数大于</span><span
lang=EN-US>65 536/4 = 16 384</span><span style='font-family:宋体'>，就需要覆盖一些已显示的字节。</span></p>

<p class=a3 style='margin-top:8.15pt;FTEL:21.45pt'><span
style='font-family:黑体'>注意：</span></p>

<p class=a1 style='FTEL:8.15pt;FTEL:21.45pt'><span
style='font-family:楷体_GB2312'>如果要在这种环境下显示较长的文件，就需要使用</span><span lang=EN-US>System.Windows.Forms</span><span
style='font-family:楷体_GB2312'>命名空间中的</span><span lang=EN-US> RichTextBox</span><span
style='font-family:楷体_GB2312'>类。</span><span lang=EN-US>RichTextBox</span><span
style='font-family:楷体_GB2312'>类似于文本框，但它有更高级的格式化功能，在显示的文本大小方面没有限制，此处使用</span><span
lang=EN-US>TextBox</span><span style='font-family:楷体_GB2312'>，是为了让示例比较简单，用户可以只考虑读取文件的过程。</span></p>

<p class=MsoNormal><span style='font-family:宋体'>在该方法中，有相当多的部分是两个嵌套的循环，它们构造出每个要显示的文本行。我们使用</span><span
lang=EN-US>StringBuilder</span><span style='font-family:宋体'>类来构造每一文本行，其性能方面的原因是：可以把每个字节的合适文本追加到表示每行文本的字符串上。如果一行上有一个新字符串，并复制构造该行时的一半字符，则不仅要花很多时间分配字符串，还会浪费堆上的许多内存。注意，可显示的字符是指字母、字或标点符号，这与相关的静态方法</span><span
lang=EN-US>System.Char</span><span style='font-family:宋体'>指定的一样。值小于</span><span
lang=EN-US>16</span><span style='font-family:宋体'>的字符都不是可显示的字符，因此回车符</span><span
lang=EN-US>(13)</span><span style='font-family:宋体'>和换行符</span><span lang=EN-US>(10)</span><span
style='font-family:宋体'>都是二进制字符</span><span lang=EN-US>(</span><span
style='font-family:宋体'>如果这些字符单独占一行，多行文本框不能正确显示它们</span><span lang=EN-US>)</span><span
style='font-family:宋体'>。</span></p>

<p class=MsoNormal><span style='font-family:宋体'>另外要注意的两点是：使用属性窗口，把文本框的字体改为固定宽度的字体——我们选择</span><span
lang=EN-US>Courier New 9pt</span><span style='font-family:宋体'>常规字体，并把文本框设置为有水平和垂直滚动条。</span></p>

<p class=MsoNormal><span style='font-family:宋体'>最后，选择流，把文本框的内容设置为已建立的字符串数组。</span></p>

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                        <div style='float:left;width:49%'>·<a href='100165769.htm'>30.2  移动、复制和删除文件</a></div><div style='float:right;width:49%'>·<a href='100165770.htm'>30.3  读写文件</a></div><div style='float:left;width:49%'>·<a href='100165771.htm'>30.3.1  流</a></div><div style='float:right;width:49%'>·<a href='100165773.htm'>30.3.3  读写文本文件</a></div><div style='float:left;width:49%'>·<a href='100165774.htm'>30.4  读写注册表</a></div><div style='float:right;width:49%'>·<a href='100165775.htm'>30.4.1  注册表</a></div></div>
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