100165355.htm
来自「C#高级编程(第三版),顶死你们。。 。up」· HTM 代码 · 共 322 行 · 第 1/4 页
HTM
322 行
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> {</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> case "N":</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> return "|| " + Norm().ToString() + " ||";</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> case "VE":</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> return String.Format("( {0:E}, {1:E}, {2:E} )", x, y, z);</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> case "IJK":</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> StringBuilder sb = new StringBuilder(x.ToString(), 30);</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> sb.Append(" i + ");</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> sb.Append(y.ToString());</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> sb.Append(" j + ");</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> sb.Append(z.ToString());</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> sb.Append(" k");</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> return sb.ToString();</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> default:</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> return ToString();</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> }</span></p>
<p class="2" style="MARGIN-TOP: 0cm; MARGIN-LEFT: 21.45pt; MARGIN-RIGHT: 0cm; FTEL: 18.45pt"><span lang="EN-US">}</span></p>
<p class="MsoNormal"><span style="FONT-FAMILY: 宋体">这就是我们需要编写的代码。注意在调用任何方法前，应防止使用格式字符串为空的参数。我们希望这个方法尽可能健壮，所有基本类型的格式说明符都是不区分大小写的，其他开发人员也希望能使用我们的类。对于格式说明符</span><span lang="EN-US">VE</span><span style="FONT-FAMILY: 宋体">，需要把每个成员格式化为科学计数法，所以再次使用</span><span lang="EN-US">String.Format ()</span><span style="FONT-FAMILY: 宋体">方法。字段</span><span lang="EN-US">x</span><span style="FONT-FAMILY: 宋体">、</span><span lang="EN-US">y</span><span style="FONT-FAMILY: 宋体">和</span><span lang="EN-US">z</span><span style="FONT-FAMILY: 宋体">都是</span><span lang="EN-US">double</span><span style="FONT-FAMILY: 宋体">类型。对于</span><span lang="EN-US">IJK</span><span style="FONT-FAMILY: 宋体">格式限定符，把几个子字符串添加到字符串中，使用</span><span lang="EN-US">StringBuilder</span><span style="FONT-FAMILY: 宋体">对象来提高性能。</span></p>
<p class="MsoNormal"><span style="FONT-FAMILY: 宋体">为了保证完整，也可以再次使用前面开发的无参数的</span><span lang="EN-US">ToString()</span><span style="FONT-FAMILY: 宋体">重载方法：</span></p>
<p class="MsoNormal"><span lang="EN-US"> </span></p>
<p class="2" style="MARGIN-TOP: 8.15pt; MARGIN-LEFT: 21.45pt; MARGIN-RIGHT: 0cm; FTEL: 18.45pt"><span lang="EN-US">public override string ToString()</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US">{</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> return "( " + x + " , " + y + " , " + z + " )"; </span></p>
<p class="2" style="MARGIN-TOP: 0cm; MARGIN-LEFT: 21.45pt; MARGIN-RIGHT: 0cm; FTEL: 18.45pt"><span lang="EN-US">}</span></p>
<p class="MsoNormal"><span style="FONT-FAMILY: 宋体">最后，需要添加一个</span><span lang="EN-US">Norm()</span><span style="FONT-FAMILY: 宋体">方法，计算矢量的平方</span><span lang="EN-US">(</span><span style="FONT-FAMILY: 宋体">模</span><span lang="EN-US">)</span><span style="FONT-FAMILY: 宋体">，因为在开发</span><span lang="EN-US">Vector</span><span style="FONT-FAMILY: 宋体">结构时，没有提供这个方法：</span></p>
<p class="2" style="MARGIN-TOP: 8.15pt; MARGIN-LEFT: 21.45pt; MARGIN-RIGHT: 0cm; FTEL: 18.45pt"><span lang="EN-US">public double Norm()</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US">{</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> return x*x + y*y + z*z;</span></p>
<p class="2" style="MARGIN-TOP: 0cm; MARGIN-LEFT: 21.45pt; MARGIN-RIGHT: 0cm; FTEL: 18.45pt"><span lang="EN-US">}</span></p>
<p class="MsoNormal"><span style="FONT-FAMILY: 宋体">下面用一些合适的测试代码测试可格式化的矢量：</span></p>
<p class="2" style="MARGIN-TOP: 8.15pt; MARGIN-LEFT: 21.45pt; MARGIN-RIGHT: 0cm; FTEL: 18.45pt"><span lang="EN-US">static void Main()</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US">{</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> Vector v1 = new Vector(1,32,5);</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> Vector v2 = new Vector(845.4, 54.3, </span><span style="FONT-FAMILY: 宋体">–</span><span lang="EN-US">7.8);</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> Console.WriteLine("\nIn IJK format,\nv1 is {0,30:IJK}\nv2 is {1,30:IJK}",</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> v1, v2);</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> Console.WriteLine("\nIn default format,\nv1 is {0,30}\nv2 is {1,30}", v1,</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> v2);</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> Console.WriteLine("\nIn VE format\nv1 is {0,30:VE}\nv2 is {1,30:VE}", v1,</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> v2);</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> Console.WriteLine("\nNorms are:\nv1 is {0,20:N}\nv2 is {1,20:N}", v1,</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> v2);</span></p>
<p class="2" style="MARGIN-TOP: 0cm; MARGIN-LEFT: 21.45pt; MARGIN-RIGHT: 0cm; FTEL: 18.45pt"><span lang="EN-US">}</span></p>
<p class="MsoNormal"><span style="FONT-FAMILY: 宋体">运行这个示例的结果如下所示：</span></p>
<p class="a6" style="MARGIN-TOP: 8.15pt; MARGIN-LEFT: 21.45pt; MARGIN-RIGHT: 0cm; FTEL: 18.45pt"><strong><span lang="EN-US">FormattableVector</span></strong></p>
<p class="a6" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US">In IJK format,</span></p>
<p class="a6" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US">v1 is 1 i + 32 j + 5 k</span></p>
<p class="a6" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US">v2 is 845.4 i + 54.3 j + -7.8 k</span></p>
<p class="a6" style="MARGIN-TOP: 6pt; MARGIN-LEFT: 21.45pt; MARGIN-RIGHT: 0cm; FTEL: 18.45pt"><span lang="EN-US">In default format,</span></p>
<p class="a6" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US">v1 is ( 1 , 32 , 5 )</span></p>
<p class="a6" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US">v2 is ( 845.4 , 54.3 , -7.8 )</span></p>
<p class="a6" style="MARGIN-TOP: 6pt; MARGIN-LEFT: 21.45pt; MARGIN-RIGHT: 0cm; FTEL: 18.45pt"><span lang="EN-US">In VE format</span></p>
<p class="a6" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US">v1 is ( 1.000000E+000, 3.200000E+001, 5.000000E+000 )</span></p>
<p class="a6" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US">v2 is ( 8.454000E+002, 5.430000E+001,</span><span style="FONT-FAMILY: 宋体">–</span><span lang="EN-US">7.800000E+000 )</span></p>
<p class="a6" style="MARGIN-TOP: 6pt; MARGIN-LEFT: 21.45pt; MARGIN-RIGHT: 0cm; FTEL: 18.45pt"><span lang="EN-US">Norms are:</span></p>
<p class="a6" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US">v1 is || 1050 ||</span></p>
<p class="a6" style="MARGIN-TOP: 0cm; MARGIN-LEFT: 21.45pt; MARGIN-RIGHT: 0cm; FTEL: 18.45pt"><span lang="EN-US">v2 is || 717710.49 ||</span></p>
<p class="MsoNormal" style="FTEL: 0cm"><span style="FONT-FAMILY: 宋体">这说明了选用的定制格式说明符是正确的。</span></p></div>
<!-- page -->
<div class="page" style="text-align: center">
<a href="100165354.htm">上一页</a> <a href="index.html">首页</a> <a href="100165356.htm">下一页</a>
</div>
<div style="margin: 0px auto; width: 700px; border: solid 1px #0b5f98;">
<div style="float: left; width: 16px; background-color: #0b5f98; color: White; padding: 1px;">
图书导读
</div>
<div style="float: right; width: 670px; text-align: left; line-height: 16pt; padding-left: 2px">
<!--导读-->
<h1 id="divCurrentNode2" style="color: #b83507; width: 100%; text-align: left; font-size: 12px; padding-left: 2px">当前章节:<a href='100165355.htm'><font color='red'>8.1.2 格式化字符串</font></a></h1>
<div id="divRealteNod2" style="padding-left: 2px">
<div style='float:left;width:49%'>·<a href='100165352.htm'>7.4 小结</a></div><div style='float:right;width:49%'>·<a href='100165353.htm'>8.1 System.String类</a></div><div style='float:left;width:49%'>·<a href='100165354.htm'>8.1.1 创建字符串</a></div><div style='float:right;width:49%'>·<a href='100165356.htm'>8.2 正则表达式</a></div><div style='float:left;width:49%'>·<a href='100165357.htm'>8.3 小结</a></div><div style='float:right;width:49%'>·<a href='100165358.htm'>9.1 对象组</a></div></div>
</div>
</div>
</div></div>
</body>
</html>
⌨️ 快捷键说明
复制代码Ctrl + C
搜索代码Ctrl + F
全屏模式F11
增大字号Ctrl + =
减小字号Ctrl + -
显示快捷键?