做过PHP开发的程序员应该清楚，PHP中有很多内置的功能，掌握了它们，可以帮助你在做PHP开发时更加得心应手，本文将分享8个开发必备的PHP功能，个个都非常实用，希望各位PHP开发者能够掌握。
1、传递任意数量的函数参数
2、使用glob()查找文件
3、获取内存使用情况信息
4、获取CPU使用情况信息
5、获取系统常量
6、生成唯一的id
7、序列化
8、字符串压缩
1、传递任意数量的函数参数 我们在.NET或者JAVA编程中，一般函数参数个数都是固定的，但是PHP允许你使用任意个数的参数。下面这个示例向你展示了PHP函数的默认参数：
<span 1</span> <span //</span><span 两个默认参数的函数 </span>
<span 2</span> <span function</span> foo(<span $arg1</span> = ", <span $arg2</span> =<span ") {
</span><span 3</span> <span echo</span> "arg1: <span $arg1</span><span \n";
</span><span 4</span> <span echo</span> "arg2: <span $arg2</span><span \n";
</span><span 5</span> <span }
</span><span 6</span> foo('hello','<span world');
</span><span 7</span> <span /* 输出:
</span><span 8</span> <span arg1: hello
</span><span 9</span> <span arg2: world
</span><span 10</span> <span */
</span><span 11</span> <span foo();
</span><span 12</span> <span /* 输出:
</span><span 13</span> <span arg1:
</span><span 14</span> <span arg2:
</span><span 15</span> <span */
</span><span 16</span> <span 下面这个示例是PHP的不定参数用法，其使用到了 func_get_args()方法：
</span><span 17</span> <span // 是的，形参列表为空
</span><span 18</span> <span function foo() {
</span><span 19</span> <span // 取得所有的传入参数的数组
</span><span 20</span> <span $args = func_get_args();
</span><span 21</span> <span foreach ($args as $k => $v) {
</span><span 22</span> <span echo "arg".($k+1).": $v\n";
</span><span 23</span> <span }
</span><span 24</span> <span }
</span><span 25</span> <span foo();
</span><span 26</span> <span /* 什么也不会输出 */
</span><span 27</span> <span foo('hello');
</span><span 28</span> <span /* 输出
</span><span 29</span> <span arg1: hello
</span><span 30</span> <span */
</span><span 31</span> <span foo('hello', 'world', 'again');
</span><span 32</span> <span /* 输出
</span><span 33</span> <span arg1: hello
</span><span 34</span> <span arg2: world
</span><span 35</span> <span arg3: again
</span><span 36</span> */
2、使用glob()查找文件 大部分PHP函数的函数名从字面上都可以理解其用途，但是当你看到 glob() 的时候，你也许并不知道这是用来做什么的，其实glob()和scandir() 一样，可以用来查找文件，请看下面的用法：
<span 1</span> <span //</span><span 取得所有的后缀为PHP的文件 </span>
<span 2</span> <span $files</span> = <span glob</span>('*.<span php');
</span><span 3</span> <span print_r</span>(<span $files</span><span );
</span><span 4</span> <span /*</span><span 输出:
</span><span 5</span> <span Array
</span><span 6</span> <span (
</span><span 7</span> <span [0] => phptest.php
</span><span 8</span> <span [1] => pi.php
</span><span 9</span> <span [2] => post_output.php
</span><span 10</span> <span [3] => test.php
</span><span 11</span> <span )
</span><span 12</span> <span */</span>
你还可以查找多种后缀名：
<span 1</span> <span //</span><span 取PHP文件和TXT文件 </span>
<span 2</span> <span $files</span> = <span glob</span>('*.{php,txt}',<span GLOB_BRACE);
</span><span 3</span> <span print_r</span>(<span $files</span><span );
</span><span 4</span> <span /*</span><span 输出:
</span><span 5</span> <span Array
</span><span 6</span> <span (
</span><span 7</span> <span [0] => phptest.php
</span><span 8</span> <span [1] => pi.php
</span><span 9</span> <span [2] => post_output.php
</span><span 10</span> <span [3] => test.php
</span><span 11</span> <span [4] => log.txt
</span><span 12</span> <span [5] => test.txt
</span><span 13</span> <span )
</span><span 14</span> <span */</span>
你还可以加上路径：
<span 1</span> <span $files</span> = <span glob</span>('../images/a*.<span jpg');
</span><span 2</span> <span print_r</span>(<span $files</span><span );
</span><span 3</span> <span /*</span><span 输出:
</span><span 4</span> <span Array
</span><span 5</span> <span (
</span><span 6</span> <span [0] => ../images/apple.jpg
</span><span 7</span> <span [1] => ../images/art.jpg
</span><span 8</span> <span )
</span><span 9</span> <span */</span>
如果你想得到绝对路径，你可以调用 realpath() 函数：
<span 1</span> <span $files</span> = <span glob</span>('../images/a*.<span jpg');
</span><span 2</span> <span //</span><span applies the function to each array element </span>
<span 3</span> <span $files</span> = <span array_map</span>('<span realpath</span>',<span $files</span><span );
</span><span 4</span> <span print_r</span>(<span $files</span><span );
</span><span 5</span> <span /*</span><span output looks like:
</span><span 6</span> <span Array
</span><span 7</span> <span (
</span><span 8</span> <span [0] => C:\wamp\www\images\apple.jpg
</span><span 9</span> <span [1] => C:\wamp\www\images\art.jpg
</span><span 10</span> <span )
</span><span 11</span> <span */</span>
3、获取内存使用情况信息 PHP的内存回收机制已经非常强大，你也可以使用PHP脚本获取当前内存的使用情况，调用memory_get_usage() 函数获取当期内存使用情况，调用memory_get_peak_usage() 函数获取内存使用的峰值。参考代码如下：
<span 1</span> <span echo</span> "Initial: ".memory_get_usage().<span " bytes \n";
</span><span 2</span> <span /*</span><span 输出
</span><span 3</span> <span Initial: 361400 bytes
</span><span 4</span> <span */</span>
<span 5</span> <span //</span><span 使用内存 </span>
<span 6</span> <span for</span> (<span $i</span> = 0; <span $i</span> < 100000; <span $i</span>++<span ) {
</span><span 7</span> <span $array</span> []= <span md5</span>(<span $i</span><span );
</span><span 8</span> <span }
</span><span 9</span> <span //</span><span 删除一半的内存 </span>
<span 10</span> <span for</span> (<span $i</span> = 0; <span $i</span> < 100000; <span $i</span>++<span ) {
</span><span 11</span> <span unset</span>(<span $array</span>[<span $i</span><span ]);
</span><span 12</span> <span }
</span><span 13</span> <span echo</span> "<span Final</span>: ".memory_get_usage().<span " bytes \n";
</span><span 14</span> <span /*</span><span prints
</span><span 15</span> <span Final: 885912 bytes
</span><span 16</span> <span */</span>
<span 17</span> <span echo</span> "Peak: ".memory_get_peak_usage().<span " bytes \n";
</span><span 18</span> <span /*</span><span 输出峰值
</span><span 19</span> <span Peak: 13687072 bytes
</span><span 20</span> <span */</span>
4、获取CPU使用情况信息 获取了内存使用情况，也可以使用PHP的 getrusage()获取CPU使用情况，该方法在windows下不可用。
<span 1</span> <span print_r</span><span (getrusage()); </span><span 2</span> <span /*</span><span 输出 </span><span 3</span> <span Array </span><span 4</span> <span ( </span><span 5</span> <span [ru_oublock] => 0 </span><span 6</span> <span [ru_inblock] => 0 </span><span 7</span> <span [ru_msgsnd] => 2 </span><span 8</span> <span [ru_msgrcv] => 3 </span><span 9</span> <span [ru_maxrss] => 12692 </span><span 10</span> <span [ru_ixrss] => 764 </span><span 11</span> <span [ru_idrss] => 3864 </span><span 12</span> <span [ru_minflt] => 94 </span><span 13</span> <span [ru_majflt] => 0 </span><span 14</span> <span [ru_nsignals] => 1 </span><span 15</span> <span [ru_nvcsw] => 67 </span><span 16</span> <span [ru_nivcsw] => 4 </span><span 17</span> <span [ru_nswap] => 0 </span><span 18</span> <span [ru_utime.tv_usec] => 0 </span><span 19</span> <span [ru_utime.tv_sec] => 0 </span><span 20</span> <span [ru_stime.tv_usec] => 6269 </span><span 21</span> <span [ru_stime.tv_sec] => 0 </span><span 22</span> <span ) </span><span 23</span> <span */</span>
这个结构看上出很晦涩，除非你对CPU很了解。下面一些解释： ru_oublock: 块输出操作 ru_inblock: 块输入操作 ru_msgsnd: 发送的message ru_msgrcv: 收到的message ru_maxrss: 最大驻留集大小 ru_ixrss: 全部共享内存大小 ru_idrss:全部非共享内存大小 ru_minflt: 页回收 ru_majflt: 页失效 ru_nsignals: 收到的信号 ru_nvcsw: 主动上下文切换 ru_nivcsw: 被动上下文切换 ru_nswap: 交换区 ru_utime.tv_usec: 用户态时间 (microseconds) ru_utime.tv_sec: 用户态时间(seconds) ru_stime.tv_usec: 系统内核时间 (microseconds) ru_stime.tv_sec: 系统内核时间?(seconds) 要看到你的脚本消耗了多少CPU，我们需要看看"用户态的时间"和"系统内核时间"的值。秒和微秒部分是分别提供的，您可以把微秒值除以100万，并把它添加到秒的值后，可以得到有小数部分的秒数。
<span 1</span> <span //</span><span sleep for 3 seconds (non-busy) </span> <span 2</span> <span sleep</span>(3<span ); </span><span 3</span> <span $data</span> =<span getrusage(); </span><span 4</span> <span echo</span> "User <span time</span>: ". <span 5</span> (<span $data</span>['ru_utime.tv_sec'] + <span 6</span> <span $data</span>['ru_utime.tv_usec'] / 1000000<span ); </span><span 7</span> <span echo</span> "<span System</span> <span time</span>: ". <span 8</span> (<span $data</span>['ru_stime.tv_sec'] + <span 9</span> <span $data</span>['ru_stime.tv_usec'] / 1000000<span ); </span><span 10</span> <span /*</span><span 输出 </span><span 11</span> <span User time: 0.011552 </span><span 12</span> <span System time: 0 </span><span 13</span> <span */</span>
是不占用系统时间的，我们可以来看下面的一个例子：
<span 1</span> <span //</span><span loop 10 million times (busy) </span>
<span 2</span> <span for</span>(<span $i</span>=0;<span $i</span><10000000;<span $i</span>++<span ) {
</span><span 3</span> <span }
</span><span 4</span> <span $data</span> =<span getrusage();
</span><span 5</span> <span echo</span> "User <span time</span>: ".
<span 6</span> (<span $data</span>['ru_utime.tv_sec'] +
<span 7</span> <span $data</span>['ru_utime.tv_usec'] / 1000000<span );
</span><span 8</span> <span echo</span> "<span System</span> <span time</span>: ".
<span 9</span> (<span $data</span>['ru_stime.tv_sec'] +
<span 10</span> <span $data</span>['ru_stime.tv_usec'] / 1000000<span );
</span><span 11</span> <span /*</span><span 输出
</span><span 12</span> <span User time: 1.424592
</span><span 13</span> <span System time: 0.004204
</span><span 14</span> <span */</span>
这花了大约14秒的CPU时间，几乎所有的都是用户的时间，因为没有系统调用。传统时间是CPU花费在系统调用上的上执行内核指令的时间。下面是一个例子：
<span 1</span> <span $start</span> = <span microtime</span>(<span true</span><span );
</span><span 2</span> <span //</span><span keep calling microtime for about 3 seconds </span>
<span 3</span> <span while</span>(<span microtime</span>(<span true</span>) – <span $start</span> < 3<span ) {
</span><span 4</span> <span }
</span><span 5</span> <span $data</span> =<span getrusage();
</span><span 6</span> <span echo</span> "User <span time</span>: ".
<span 7</span> (<span $data</span>['ru_utime.tv_sec'] +
<span 8</span> <span $data</span>['ru_utime.tv_usec'] / 1000000<span );
</span><span 9</span> <span echo</span> "<span System</span> <span time</span>: ".
<span 10</span> (<span $data</span>['ru_stime.tv_sec'] +
<span 11</span> <span $data</span>['ru_stime.tv_usec'] / 1000000<span );
</span><span 12</span> <span /*</span><span prints
</span><span 13</span> <span User time: 1.088171
</span><span 14</span> <span System time: 1.675315
</span><span 15</span> <span */</span>
我们可以看到上面这个例子更耗CPU。
5、获取系统常量 PHP 提供非常有用的系统常量 可以让你得到当前的行号 (__LINE__)，文件 (__FILE__)，目录 (__DIR__)，函数名 (__FUNCTION__)，类名(__CLASS__)，方法名(__METHOD__) 和名字空间 (__NAMESPACE__)，很像C语言。
我们可以以为这些东西主要是用于调试，当也不一定，比如我们可以在include其它文件的时候使用?__FILE__ (当然，你也可以在 PHP 5.3以后使用 __DIR__ )，下面是一个例子。
<span 1</span> <span //</span><span this is relative to the loaded script's path
</span><span 2</span> <span // it may cause problems when running scripts from different directories </span>
<span 3</span> <span require_once</span>('config/database.<span php');
</span><span 4</span> <span //</span><span this is always relative to this file's path
</span><span 5</span> <span // no matter where it was included from </span>
<span 6</span> <span require_once</span>(<span dirname</span>(<span __FILE__</span>) . '/config/database.php');
下面是使用 __LINE__ 来输出一些debug的信息，这样有助于你调试程序：
<span 1</span> <span //</span><span some code
</span><span 2</span> <span // … </span>
<span 3</span> my_debug("some debug message", <span __LINE__</span><span );
</span><span 4</span> <span /*</span><span 输出
</span><span 5</span> <span Line 4: some debug message
</span><span 6</span> <span */</span>
<span 7</span> <span //</span><span some more code
</span><span 8</span> <span // … </span>
<span 9</span> my_debug("another debug message", <span __LINE__</span><span );
</span><span 10</span> <span /*</span><span 输出
</span><span 11</span> <span Line 11: another debug message
</span><span 12</span> <span */</span>
<span 13</span> <span function</span> my_debug(<span $msg</span>, <span $line</span><span ) {
</span><span 14</span> <span echo</span> "Line <span $line</span>: <span $msg</span><span \n";
</span><span 15</span> }
6、生成唯一的id 很多朋友都利用md5()来生成唯一的编号，但是md5()有几个缺点：1、无序，导致数据库中排序性能下降。2、太长，需要更多的存储空间。其实PHP中自带一个函数来生成唯一的id，这个函数就是uniqid()。下面是用法：
<span 1</span> <span //</span><span generate unique string </span> <span 2</span> <span echo</span> <span uniqid</span><span (); </span><span 3</span> <span /*</span><span 输出 </span><span 4</span> <span 4bd67c947233e </span><span 5</span> <span */</span> <span 6</span> <span //</span><span generate another unique string </span> <span 7</span> <span echo</span> <span uniqid</span><span (); </span><span 8</span> <span /*</span><span 输出 </span><span 9</span> <span 4bd67c9472340 </span><span 10</span> <span */</span>
该算法是根据CPU时间戳来生成的，所以在相近的时间段内，id前几位是一样的，这也方便id的排序，如果你想更好的避免重复，可以在id前加上前缀，如：
<span 1</span> <span //</span><span 前缀 </span>
<span 2</span> <span echo</span> <span uniqid</span><span ('foo_');
</span><span 3</span> <span /*</span><span 输出
</span><span 4</span> <span foo_4bd67d6cd8b8f
</span><span 5</span> <span */</span>
<span 6</span> <span //</span><span 有更多的熵 </span>
<span 7</span> <span echo</span> <span uniqid</span>(",<span true</span><span );
</span><span 8</span> <span /*</span><span 输出
</span><span 9</span> <span 4bd67d6cd8b926.12135106
</span><span 10</span> <span */</span>
<span 11</span> <span //</span><span 都有 </span>
<span 12</span> <span echo</span> <span uniqid</span>('bar_',<span true</span><span );
</span><span 13</span> <span /*</span><span 输出
</span><span 14</span> <span bar_4bd67da367b650.43684647
</span><span 15</span> <span */</span>
7、序列化 PHP序列化功能大家可能用的比较多，也比较常见，当你需要把数据存到数据库或者文件中是，你可以利用PHP中的serialize() 和 unserialize()方法来实现序列化和反序列化，代码如下：
<span 1</span> <span //</span><span 一个复杂的数组 </span>
<span 2</span> <span $myvar</span> = <span array</span><span (
</span><span 3</span> 'hello',
<span 4</span> 42,
<span 5</span> <span array</span>(1,'two'),
<span 6</span> <span 'apple'
</span><span 7</span> <span );
</span><span 8</span> <span //</span><span 序列化 </span>
<span 9</span> <span $string</span> = <span serialize</span>(<span $myvar</span><span );
</span><span 10</span> <span echo</span> <span $string</span><span ;
</span><span 11</span> <span /*</span><span 输出
</span><span 12</span> <span a:4:{i:0;s:5:"hello";i:1;i:42;i:2;a:2:{i:0;i:1;i:1;s:3:"two";}i:3;s:5:"apple";}
</span><span 13</span> <span */</span>
<span 14</span> <span //</span><span 反序例化 </span>
<span 15</span> <span $newvar</span> = <span unserialize</span>(<span $string</span><span );
</span><span 16</span> <span print_r</span>(<span $newvar</span><span );
</span><span 17</span> <span /*</span><span 输出
</span><span 18</span> <span Array
</span><span 19</span> <span (
</span><span 20</span> <span [0] => hello
</span><span 21</span> <span [1] => 42
</span><span 22</span> <span [2] => Array
</span><span 23</span> <span (
</span><span 24</span> <span [0] => 1
</span><span 25</span> <span [1] => two
</span><span 26</span> <span )
</span><span 27</span> <span [3] => apple
</span><span 28</span> <span )
</span><span 29</span> <span */</span>
如何序列化成json格式呢，放心，php也已经为你做好了，使用php 5.2以上版本的用户可以使用json_encode() 和 json_decode() 函数来实现json格式的序列化，代码如下：
<span 1</span> <span //</span><span a complex array </span> <span 2</span> <span $myvar</span> = <span array</span><span ( </span><span 3</span> 'hello', <span 4</span> 42, <span 5</span> <span array</span>(1,'two'), <span 6</span> <span 'apple' </span><span 7</span> <span ); </span><span 8</span> <span //</span><span convert to a string </span> <span 9</span> <span $string</span> = json_encode(<span $myvar</span><span ); </span><span 10</span> <span echo</span> <span $string</span><span ; </span><span 11</span> <span /*</span><span prints </span><span 12</span> <span ["hello",42,[1,"two"],"apple"] </span><span 13</span> <span */</span> <span 14</span> <span //</span><span you can reproduce the original variable </span> <span 15</span> <span $newvar</span> = json_decode(<span $string</span><span ); </span><span 16</span> <span print_r</span>(<span $newvar</span><span ); </span><span 17</span> <span /*</span><span prints </span><span 18</span> <span Array </span><span 19</span> <span ( </span><span 20</span> <span [0] => hello </span><span 21</span> <span [1] => 42 </span><span 22</span> <span [2] => Array </span><span 23</span> <span ( </span><span 24</span> <span [0] => 1 </span><span 25</span> <span [1] => two </span><span 26</span> <span ) </span><span 27</span> <span [3] => apple </span><span 28</span> <span ) </span><span 29</span> <span */</span>
8、字符串压缩 当我们说到压缩，我们可能会想到文件压缩，其实，字符串也是可以压缩的。PHP提供了 gzcompress() 和gzuncompress() 函数：
<span 1</span> <span $string</span> = <span 2</span> "Lorem ipsum dolor sit amet,<span consectetur </span><span 3</span> adipiscing elit.<span Nunc ut elit id mi ultricies </span><span 4</span> adipiscing. Nulla facilisi. Praesent pulvinar, <span 5</span> sapien vel feugiat vestibulum, nulla dui pretium orci, <span 6</span> non ultricies elit lacus quis ante.<span Lorem ipsum dolor </span><span 7</span> sit amet, consectetur adipiscing elit.<span Aliquam </span><span 8</span> pretium ullamcorper urna quis iaculis.<span Etiam ac massa </span><span 9</span> sed turpis tempor luctus.<span Curabitur sed nibh eu elit </span><span 10</span> mollis congue. Praesent ipsum diam,<span consectetur vitae </span><span 11</span> ornare a, aliquam a nunc.<span In id magna pellentesque </span><span 12</span> tellus posuere adipiscing. Sed non mi metus,<span at lacinia </span><span 13</span> augue. Sed magna nisi, ornare in mollis in,<span mollis </span><span 14</span> sed nunc. Etiam at justo in leo congue mollis. <span 15</span> <span Nullam in neque eget metus hendrerit scelerisque </span><span 16</span> eu non enim.<span Ut malesuada lacus eu nulla bibendum </span><span 17</span> id euismod urna sodales.<span "; </span><span 18</span> <span $compressed</span> = <span gzcompress</span>(<span $string</span><span ); </span><span 19</span> <span echo</span> "Original size: ". <span strlen</span>(<span $string</span>).<span "\n"; </span><span 20</span> <span /*</span><span 输出原始大小 </span><span 21</span> <span Original size: 800 </span><span 22</span> <span */</span> <span 23</span> <span echo</span> "Compressed size: ". <span strlen</span>(<span $compressed</span>).<span "\n"; </span><span 24</span> <span /*</span><span 输出压缩后的大小 </span><span 25</span> <span Compressed size: 418 </span><span 26</span> <span */</span> <span 27</span> <span //</span><span 解压缩 </span> <span 28</span> <span $original</span> = <span gzuncompress</span>(<span $compressed</span>);
几乎有50% 压缩比率。同时，你还可以使用 gzencode() 和 gzdecode() 函数来压缩，只不用其用了不同的压缩算法。
以上就是8个开发必备的PHP功能，是不是都很实用呢？
原文出处:http://www.codeceo.com/8-php-functions.html
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