介绍10个非常有用的PHP函数_PHP教程-php教程-PHP中文网

介绍10个非常有用的PHP函数_PHP教程

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发布： 2016-07-20 10:57:25

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函数是php如此强大的源泉，但是很多php函数并没有得到充分的利用。这里，我们给大家简单介绍10个不常见，但非常有用的函数。

1、sys_getloadavg()

sys_getloadavt()可以获得系统负载情况。该函数返回一个包含三个元素的数组，每个元素分别代表系统再过去的1、5和15分钟内的平均负载。与其让服务器因负载过高而宕掉，不如在系统负载很高时主动die掉一个脚本，sys_getloadavg()就是用来帮你实现这个功能的。不过很遗憾，该函数在windows下无效。

2、pack()

Pack() 能将md5()返回的32位16进制字符串转换为16位的二进制字符串，可以节省存储空间。

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3、cal_days_in_month()

cal_days_in_month()能够返回指定月份共有多少天。

4、_()

WordPress开发者经常能见到这个函数，还有 _e()。这两个函数功能相同，与gettext()函数结合使用，能实现网站的多语言化。具体可参见PHP手册的相关部分介绍。

5、get_browser()

在发送页面前先看看用户的浏览器都能做些什么是不是挺好?get_browser()能获得用户的浏览器类型，以及浏览器支持的功能，不过首先你需要一个php_browscap.ini文件，用来给函数做参考文件。

要注意，该函数对浏览器功能的判断是基于该类浏览器的一般特性的。例如，如果用户关闭了浏览器对 JavaScript的支持，函数无法得知这一点。但是在判断浏览器类型和OS平台方面，该函数还是很准确的。

6、debug_print_backtrace()

这是一个调试用的函数，能帮助你发现代码中的逻辑错误。要理解这个函数，还是直接看个例子吧：

<ol class="dp-c"><li class="alt"><span><span class="vars">$a</span><span> = 0;   </span></span></li><li><span class="keyword">function</span><span> iterate() {   </span></li><li class="alt"><span class="keyword">global</span><span> </span><span class="vars">$a</span><span>;   </span></li><li><span class="keyword">if</span><span>( </span><span class="vars">$a</span><span> < 10 )   </span></li><li class="alt"><span>recur();   </span></li><li><span class="func">echo</span><span> </span><span class="vars">$a</span><span> . &ldquo;, &ldquo;;   </span></li><li class="alt"><span>}   </span></li><li><span class="keyword">function</span><span> recur() {   </span></li><li class="alt"><span class="keyword">global</span><span> </span><span class="vars">$a</span><span>;   </span></li><li><span class="vars">$a</span><span>++;   </span></li><li class="alt"><span class="comment">// how did I get here?  </span><span> </span></li><li><span class="func">echo</span><span> &ldquo;nnn&rdquo;;   </span></li><li class="alt"><span>debug_print_backtrace();   </span></li><li><span class="keyword">if</span><span>( </span><span class="vars">$a</span><span> < 10 )   </span></li><li class="alt"><span>iterate();   </span></li><li><span>}   </span></li><li class="alt"><span>iterate();   </span></li><li><span># OUTPUT:   </span></li><li class="alt"><span>#0 recur() called at [C:htdocsphp_stuffindex.php:8]   </span></li><li><span>#1 iterate() called at [C:htdocsphp_stuffindex.php:25]   </span></li><li class="alt"><span>#0 recur() called at [C:htdocsphp_stuffindex.php:8]   </span></li><li><span>#1 iterate() called at [C:htdocsphp_stuffindex.php:21]   </span></li><li class="alt"><span>#2 recur() called at [C:htdocsphp_stuffindex.php:8]   </span></li><li><span>#3 iterate() called at [C:htdocsphp_stuffindex.php:25]   </span></li><li class="alt"><span>#0 recur() called at [C:htdocsphp_stuffindex.php:8]   </span></li><li><span>#1 iterate() called at [C:htdocsphp_stuffindex.php:21]   </span></li><li class="alt"><span>#2 recur() called at [C:htdocsphp_stuffindex.php:8]   </span></li><li><span>#3 iterate() called at [C:htdocsphp_stuffindex.php:21]   </span></li><li class="alt"><span>#4 recur() called at [C:htdocsphp_stuffindex.php:8]   </span></li><li><span>#5 iterate() called at [C:htdocsphp_stuffindex.php:25] </span></li></ol>

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7、metaphone()

这个函数返回单词的metaphone值，相同读音的单词具有相同的metaphone值，也就是说这个函数可以帮你判断两个单词的读音是否相同。

8、natsort()

natsort()能将一个数组以自然排序法进行排列，直接看个例子吧：

<ol class="dp-c"><li class="alt"><span><span class="vars">$items</span><span> = </span><span class="keyword">array</span><span>(   </span></span></li><li><span>&ldquo;100 apples&rdquo;, &ldquo;5 apples&rdquo;, &ldquo;110 apples&rdquo;, &ldquo;55 apples&rdquo;   </span></li><li class="alt"><span>);   </span></li><li><span class="comment">// normal sorting:  </span><span> </span></li><li class="alt"><span>sort(</span><span class="vars">$items</span><span>);   </span></li><li><span>print_r(</span><span class="vars">$items</span><span>);   </span></li><li class="alt"><span># Outputs:   </span></li><li><span># Array   </span></li><li class="alt"><span># (   </span></li><li><span># [0] => 100 apples   </span></li><li class="alt"><span># [1] => 110 apples   </span></li><li><span># [2] => 5 apples   </span></li><li class="alt"><span># [3] => 55 apples   </span></li><li><span># )   </span></li><li class="alt"><span>natsort(</span><span class="vars">$items</span><span>);   </span></li><li><span>print_r(</span><span class="vars">$items</span><span>);   </span></li><li class="alt"><span># Outputs:   </span></li><li><span># Array   </span></li><li class="alt"><span># (   </span></li><li><span># [2] => 5 apples   </span></li><li class="alt"><span># [3] => 55 apples   </span></li><li><span># [0] => 100 apples   </span></li><li class="alt"><span># [1] => 110 apples   </span></li><li><span># ) </span></li></ol>

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9、levenshtein()

Levenshtein()告诉你两个单词之间的“距离”。它告诉你如果想把一个单词变成另一个单词，需要插入、替换和删除多少字母。

看个例子吧：

<ol class="dp-c"><li class="alt"><span><span class="vars">$dictionary</span><span> = </span><span class="keyword">array</span><span>(   </span></span></li><li><span>&ldquo;php&rdquo;, &ldquo;javascript&rdquo;, &ldquo;css&rdquo;   </span></li><li class="alt"><span>);   </span></li><li><span class="vars">$word</span><span> = &ldquo;japhp&rdquo;;   </span></li><li class="alt"><span class="vars">$best_match</span><span> = </span><span class="vars">$dictionary</span><span>[0];   </span></li><li><span class="vars">$match_value</span><span> = levenshtein(</span><span class="vars">$dictionary</span><span>[0], </span><span class="vars">$word</span><span>);   </span></li><li class="alt"><span class="keyword">foreach</span><span>(</span><span class="vars">$dictionary</span><span> </span><span class="keyword">as</span><span> </span><span class="vars">$w</span><span>) {   </span></li><li><span class="vars">$value</span><span> = levenshtein(</span><span class="vars">$word</span><span>, </span><span class="vars">$w</span><span>);   </span></li><li class="alt"><span class="keyword">if</span><span>( </span><span class="vars">$value</span><span> < </span><span class="vars">$match_value</span><span> ) {   </span></li><li><span class="vars">$best_match</span><span> = </span><span class="vars">$w</span><span>;   </span></li><li class="alt"><span class="vars">$match_value</span><span> = </span><span class="vars">$value</span><span>;   </span></li><li><span>}   </span></li><li class="alt"><span>}   </span></li><li><span class="func">echo</span><span> &ldquo;Did you mean the &lsquo;</span><span class="vars">$best_match</span><span>&rsquo; category?&rdquo;; </span></li></ol>

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10、glob()

glob()会让你觉得用 opendir(), readdir()和closedir()来寻找文件非常蠢。

<ol class="dp-c"><li class="alt"><span><span class="keyword">foreach</span><span> (</span><span class="func">glob</span><span>(&ldquo;*.php&rdquo;) </span><span class="keyword">as</span><span> </span><span class="vars">$file</span><span>)   </span></span></li><li><span class="func">echo</span><span> &ldquo;</span><span class="vars">$file</span><span>n&rdquo;; </span></li></ol>

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希望本文介绍的这10个PHP函数，能够帮助到你，更好的使用PHP。