以前做过一道php面试题是这样的：不使用第三个变量实现交换两个变量的值。一般都是借助第三个中间变量来实现原来两个变量的值交换，但是这道题却要求不能使用中间变量，这对于初学者来说也算是一个难题了。网上找到的几种方法总结如下：
<span><span> <span>="a"<span><span>="b"<span><span echo> '交换前 $a:'.<span>.',$b:'.<span>.'<br />'<span><span>.=<span><span><span>=<span substr>(<span>,0,(<span strlen>(<span>)-<span strlen>(<span><span><span>=<span substr>(<span>, <span strlen>(<span><span><span echo> '交换后$a:'.<span>.',$b:'.<span>.'<br />'<span><span echo> '-----------------------<br/>'<span><span><span> <span>="a"<span><span>="b"<span><span echo> '交换前 $a:'.<span>.',$b:'.<span>.'<br />'<span><span>.=<span><span><span>=<span str_replace>(<span>, "", <span><span><span>=<span str_replace>(<span>, "", <span><span><span echo> '交换后$a:'.<span>.',$b:'.<span>.'<br />'<span><span echo> '-----------------------<br/>'<span><span><span> <span>="a"<span><span>="b"<span><span echo> '交换前 $a:'.<span>.',$b:'.<span>.'<br />'<span><span list>(<span>,<span>)=<span array>(<span>,<span><span><span echo> '交换后$a:'.<span>.',$b:'.<span>.'<br />'<span><span echo> '-----------------------<br/>'<span><span><span> <span>='a'<span><span>='b'<span><span echo> '交换前 $a:'.<span>.',$b:'.<span>.'<br />'<span><span>=<span>^<span><span><span>=<span>^<span><span><span>=<span>^<span><span><span echo> '交换后$a:'.<span>.',$b:'.<span>.'<br />'<span><span echo> '-----------------------<br/>'<span><span><span> <span>=3<span><span>=5<span><span echo> '交换前 $a:'.<span>.',$b:'.<span>.'<br />'<span><span>=<span>+<span><span><span>=<span>-<span><span><span>=<span>-<span><span><span echo> '交换后$a:'.<span>.',$b:'.<span>.'<br />';</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span>
Perl学习手札 chm版
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Perl学习手札是台湾perl高手写的一篇文章，特打包为chm版，方便大家阅读。 关于本书 1. 关于Perl 1.1 Perl的历史 1.2 Perl的概念 1.3 特色 1.4 使用Perl的环境 1.5 开始使用 Perl 1.6 你的第一个Perl程序 2. 标量变量(Scalar) 2.1 关于标量 2.1.1 数值 2.1.2 字符串 2.1.3 数字与字符串转换 2.2 使用你自己的变量 2.3 赋值 2.3.1 直接设定 2.3.2 还可以这样 2.4 运算 2.5 变量的输出/输入 2.
