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Homephp教程php手册四个PHP非常实用的功能

这篇文章主要介绍了四个PHP非常实用的功能,需要的朋友可以参考下

最近写的几个PHP实用功能整理了一下,弄成一个文档,写上说明,方便以后使用!一共有4个PHP实用功能,现在跟大家分享,喜欢的朋友可以把它收藏起来,说不定以后用得上。

1. PHP函数的任意数目的参数
您可能知道PHP允许你定义一个默认参数的函数。但您可能并不知道PHP还允许你定义一个完全任意的参数的函数
下面是一个示例向你展示了默认参数的函数:

// 两个默认参数的函数 function foo($arg1 = '', $arg2 = '') { echo "arg1: $arg1\n"; echo "arg2: $arg2\n"; } foo('hello','world'); /* 输出: arg1: hello arg2: world */ foo(); /* 输出: arg1: arg2: */

现在我们来看一看一个不定参数的函数,其使用到了func_get_args()方法:

// 是的,形参列表为空 function foo() { // 取得所有的传入参数的数组 $args = func_get_args(); foreach ($args as $k => $v) { echo "arg".($k+1).": $v\n"; } } foo(); /* 什么也不会输出 */ foo('hello'); /* 输出 arg1: hello */ foo('hello', 'world', 'again'); /* 输出 arg1: hello arg2: world arg3: again */

2. Glob() 查找文件
 有很多PHP的函数都有一个比较长的自解释的函数名,但是,当您看到glob() 的时候,您可能并不知道这个函数是用来干什么的,除非您对它已经很熟悉了。 
你可以认为这个函数就好?scandir() 一样,其可以用来查找文件。

// 取得所有的后缀为PHP的文件 $files = glob('*.php'); print_r($files); /* 输出: Array ( [0] => phptest.php [1] => pi.php [2] => post_output.php [3] => test.php ) */

您还可以查找多种后缀名

// 取PHP文件和TXT文件 $files = glob('*.{php,txt}', GLOB_BRACE); print_r($files); /* 输出: Array ( [0] => phptest.php [1] => pi.php [2] => post_output.php [3] => test.php [4] => log.txt [5] => test.txt ) */


 您还可以加上路径: 

$files = glob('../images/a*.jpg'); print_r($files); /* 输出: Array ( [0] => ../images/apple.jpg [1] => ../images/art.jpg ) */

如果你想得到绝对路径,,你可以调用?realpath() 函数:

$files = glob('../images/a*.jpg'); // applies the function to each array element $files = array_map('realpath',$files); print_r($files); /* output looks like: Array ( [0] => C:\wamp\www\images\apple.jpg [1] => C:\wamp\www\images\art.jpg ) */

3. 查看内存使用情况
观察你程序的内存使用能够让你更好的优化你的代码。
PHP 是有垃圾回收机制的,而且有一套很复杂的内存管理机制。你可以知道你的脚本所使用的内存情况。要知道当前内存使用情况,你可以使用?memory_get_usage() 函数,如果你想知道使用内存的峰值,你可以调用memory_get_peak_usage() 函数。

echo "Initial: ".memory_get_usage()." bytes \n"; /* 输出 Initial: 361400 bytes */ // 使用内存 for ($i = 0; $i

4. 查看CPU使用情况 
使用?getrusage() 函数可以让你知道CPU的使用情况。注意,这个功能在Windows下不可用。

print_r(getrusage()); /* 输出 Array ( [ru_oublock] => 0 [ru_inblock] => 0 [ru_msgsnd] => 2 [ru_msgrcv] => 3 [ru_maxrss] => 12692 [ru_ixrss] => 764 [ru_idrss] => 3864 [ru_minflt] => 94 [ru_majflt] => 0 [ru_nsignals] => 1 [ru_nvcsw] => 67 [ru_nivcsw] => 4 [ru_nswap] => 0 [ru_utime.tv_usec] => 0 [ru_utime.tv_sec] => 0 [ru_stime.tv_usec] => 6269 [ru_stime.tv_sec] => 0 ) */

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)

以上就是分享给大家的PHP实用功能,希望对大家的学习有所帮助。

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