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2.11 控制台I/O
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C#高级编程（第3版）【全文连载】
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2.11 控制台I/O
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2006-8-17 16:57:00
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<h1 id="divCurrentNode" style="color: #b83507; width: 100%; text-align: left; font-size: 12px; padding-left: 2px">当前章节:<a href='100162748.htm'><font color='red'>2.11 控制台I/O</font></a></h1>
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<div style='float:left;width:49%'>·<a href='100162745.htm'>2.8 命名空间</a></div><div style='float:right;width:49%'>·<a href='100162746.htm'>2.9 Main()方法</a></div><div style='float:left;width:49%'>·<a href='100162747.htm'>2.10 有关编译C#文件的更多内容</a></div><div style='float:right;width:49%'>·<a href='100162749.htm'>2.12 使用注释</a></div><div style='float:left;width:49%'>·<a href='100162750.htm'>2.13 C#预处理器指令</a></div><div style='float:right;width:49%'>·<a href='100162751.htm'>2.14 C#编程规则</a></div></div>
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<div id="text"> <link href="css.css" rel="stylesheet" type="text/css" /><p class="MsoNormal" style="LINE-HEIGHT: 17pt"><span style="FONT-FAMILY: 宋体">现在，您应基本熟悉了</span><span lang="EN-US">C#</span><span style="FONT-FAMILY: 宋体">的数据类型以及如何在操作这些数据类型的程序中完成任务。本章还要使用</span><span lang="EN-US">Console</span><span style="FONT-FAMILY: 宋体">类的几个静态方法来读写数据，这些方法在编写基本的</span><span lang="EN-US">C#</span><span style="FONT-FAMILY: 宋体">程序时非常有效，下面就详细介绍它们。</span></p>
<p class="MsoNormal" style="LINE-HEIGHT: 17pt"><span style="FONT-FAMILY: 宋体">要从控制台窗口读取一行文本，可以使用</span><span lang="EN-US">Console.ReadLine()</span><span style="FONT-FAMILY: 宋体">方法，它会从控制台窗口读取一个输入流</span><span lang="EN-US">(</span><span style="FONT-FAMILY: 宋体">在用户按下回车键时停止</span><span lang="EN-US">)</span><span style="FONT-FAMILY: 宋体">，并返回输入的字符串。写入控制台也有两个对应的方法，前面已经使用过它们：</span></p>
<p class="1" style="MARGIN-LEFT: 37.55pt; TEXT-INDENT: -16.1pt"><span lang="EN-US">●<span style="FONT: 7pt 'Times New Roman'"> </span></span><span lang="EN-US">Console. Write()</span><span style="FONT-FAMILY: 宋体">方法将指定的值写入控制台窗口。</span></p>
<p class="1" style="MARGIN-LEFT: 37.55pt; TEXT-INDENT: -16.1pt"><span lang="EN-US">●<span style="FONT: 7pt 'Times New Roman'"> </span></span><span lang="EN-US">Console.WriteLine()</span><span style="FONT-FAMILY: 宋体">方法类似，但在输出结果的最后添加一个换行符。</span></p>
<p class="MsoNormal" style="LINE-HEIGHT: 17pt"><span style="FONT-FAMILY: 宋体">所有预定义类型</span><span lang="EN-US">(</span><span style="FONT-FAMILY: 宋体">包括</span><span lang="EN-US">object)</span><span style="FONT-FAMILY: 宋体">的这些函数都有各种形式</span><span lang="EN-US">(</span><span style="FONT-FAMILY: 宋体">重载</span><span lang="EN-US">)</span><span style="FONT-FAMILY: 宋体">，所以在大多数情况下，在显示值之前不必把它们转换为字符串。</span></p>
<p class="MsoNormal" style="LINE-HEIGHT: 17pt"><span style="FONT-FAMILY: 宋体">例如，下面的代码允许用户输入一行文本，并显示该文本：</span></p>
<p class="2" style="MARGIN: 8.15pt 0cm 0pt 21.45pt; TEXT-INDENT: 18.45pt"><span lang="EN-US">string s = Console.ReadLine();</span></p>
<p class="2" style="MARGIN: 0cm 0cm 8.15pt 21.45pt; TEXT-INDENT: 18.45pt"><span lang="EN-US">Console.WriteLine(s);</span></p>
<p class="MsoNormal"><span></span><span><span lang="EN-US">Console.WriteLine()</span></span><span style="FONT-FAMILY: 宋体">还允许用与</span><span lang="EN-US">C</span><span style="FONT-FAMILY: 宋体">的</span><span lang="EN-US">printf</span><span style="FONT-FAMILY: 宋体">函数类似的方式显示格式化的结果。要以这种方式使用</span><span lang="EN-US">WriteLine()</span><span style="FONT-FAMILY: 宋体">，应传入许多参数。第一个参数是花括号中包含标记的字符串，在这个花括号中，要把后续的参数插入到文本中。每个标记都包含一个基于</span><span lang="EN-US">0</span><span style="FONT-FAMILY: 宋体">的索引，表示列表中参数的序号。例如，</span><span lang="EN-US">"{0}"</span><span style="FONT-FAMILY: 宋体">表示列表中的第一个参数，所以下面的代码：</span></p>
<p class="2" style="MARGIN: 8.15pt 0cm 0pt 21.45pt; TEXT-INDENT: 18.45pt"><span lang="EN-US">int i = 10;</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; TEXT-INDENT: 18.45pt"><span lang="EN-US">int j = 20;</span></p>
<p class="2" style="MARGIN: 0cm 0cm 8.15pt 21.45pt; TEXT-INDENT: 18.45pt"><span lang="EN-US">Console.WriteLine("{0} plus {1} equals {2}", i, j, i + j);</span></p>
<p class="MsoToc1"><span style="FONT-FAMILY: 宋体">会显示：</span></p>
<p class="a6" style="MARGIN: 8.15pt 0cm 8.15pt 21.45pt; TEXT-INDENT: 18.45pt"><span lang="EN-US">10 plus 20 equals 30</span></p>
<p class="MsoNormal"><span style="FONT-FAMILY: 宋体">也可以为值指定宽度，调整文本在该宽度中的位置，正值表示右对齐，负值表示左对齐。为此可以使用格式</span><span lang="EN-US">{n,w}</span><span style="FONT-FAMILY: 宋体">，其中</span><span lang="EN-US">n</span><span style="FONT-FAMILY: 宋体">是参数索引，</span><span lang="EN-US">w</span><span style="FONT-FAMILY: 宋体">是宽度值。</span></p>
<p class="2" style="MARGIN: 8.15pt 0cm 0pt 21.45pt; TEXT-INDENT: 18.45pt"><span lang="EN-US">int i = 940;</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; TEXT-INDENT: 18.45pt"><span lang="EN-US">int j = 73;</span></p>
<p class="2" style="MARGIN: 0cm 0cm 8.15pt 21.45pt; TEXT-INDENT: 18.45pt"><span lang="EN-US">Console.WriteLine(" {0,4}\n+{1,4}\n</span><span style="FONT-FAMILY: 宋体; LETTER-SPACING: -0.9pt">––––</span><span lang="EN-US">\n {2,4}", i, j, i + j);</span></p>
<p class="MsoToc1"><span style="FONT-FAMILY: 宋体">结果如下：</span></p>
<p class="a6" style="MARGIN: 8.15pt 0cm 0pt 21.45pt; TEXT-INDENT: 18.45pt"><span lang="EN-US"> 940</span></p>
<p class="a6" style="MARGIN-LEFT: 21.45pt; TEXT-INDENT: 18.45pt"><span lang="EN-US">+ 73</span></p>
<p class="a6" style="MARGIN-LEFT: 21.45pt; TEXT-INDENT: 18.45pt"><span lang="EN-US"> </span><span style="FONT-FAMILY: 宋体; LETTER-SPACING: -1.1pt">––––</span></p>
<p class="a6" style="MARGIN: 0cm 0cm 8.15pt 21.45pt; TEXT-INDENT: 18.45pt"><span lang="EN-US"> 1013</span></p>
<p class="MsoNormal"><span style="FONT-FAMILY: 宋体">最后，还可以添加一个格式字符串，和一个可选的精度值。这里没有列出可用格式字符串的完整列表，因为如第</span><span lang="EN-US">8</span><span style="FONT-FAMILY: 宋体">章所述，我们可以定义自己的格式字符串。但用于预定义类型的主要格式字符串如表</span><span lang="EN-US">2-14</span><span style="FONT-FAMILY: 宋体">所示。</span></p>
<p class="a5" style="MARGIN-TOP: 8.15pt"><span><span style="FONT-FAMILY: 黑体">表</span><span lang="EN-US"> 2-14</span></span></p>
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<p class="a2" style="TEXT-JUSTIFY: inter-ideograph; TEXT-ALIGN: justify"><span style="FONT-FAMILY: 黑体">字</span><span style="FONT-FAMILY: 'Times New Roman'"> </span><span style="FONT-FAMILY: 黑体">符</span><span style="FONT-FAMILY: 'Times New Roman'"> </span><span style="FONT-FAMILY: 黑体">串</span></p>
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<p class="a2"><span style="FONT-FAMILY: 黑体">说</span><span lang="EN-US" style="FONT-FAMILY: 'Times New Roman'"> </span><span style="FONT-FAMILY: 黑体">明</span></p>
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<p class="a4" style="MARGIN-LEFT: 10.7pt"><span lang="EN-US">C</span></p>
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<p class="a4" style="MARGIN-LEFT: 0cm"><span style="FONT-FAMILY: 宋体">本地货币格式</span></p>
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