8个必备的PHP功能开发，必备php_PHP教程

// 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:
*/ 

// 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
*/
 
 

// 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
)
*/
 
你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
13.
)
*/
 

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

$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
)
*/
 

echo “Initial: “.memory_get_usage().” bytes \n”; 
/* 输出
Initial: 361400 bytes
*/ 
// 使用内存 
for ($i = 0; $i < 100000; $i++) { 
$array []= md5($i); 
} 
// 删除一半的内存 
for ($i = 0; $i < 100000; $i++) { 
unset($array[$i]); 
} 
echo “Final: “.memory_get_usage().” bytes \n”; 
/* prints
Final: 885912 bytes
*/ 
echo “Peak: “.memory_get_peak_usage().” bytes \n”; 
/* 输出峰值
Peak: 13687072 bytes
*/

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
)
*/
 

// sleep for 3 seconds (non-busy) 
sleep(3); 
$data = getrusage(); 
echo “User time: “. 
($data['ru_utime.tv_sec'] + 
$data['ru_utime.tv_usec'] / 1000000); 
echo “System time: “. 
($data['ru_stime.tv_sec'] + 
$data['ru_stime.tv_usec'] / 1000000); 
/* 输出
User time: 0.011552
System time: 0
*/
sleep是不占用系统时间的，我们可以来看下面的一个例子： 
// loop 10 million times (busy) 
for($i=0;$i<10000000;$i++) { 
} 
$data = getrusage(); 
echo “User time: “. 
($data['ru_utime.tv_sec'] + 
$data['ru_utime.tv_usec'] / 1000000); 
echo “System time: “. 
($data['ru_stime.tv_sec'] + 
$data['ru_stime.tv_usec'] / 1000000); 
/* 输出
User time: 1.424592
System time: 0.004204
*/

$start = microtime(true); 
// keep calling microtime for about 3 seconds 
while(microtime(true) – $start < 3) { 
} 
$data = getrusage(); 
echo “User time: “. 
($data['ru_utime.tv_sec'] + 
$data['ru_utime.tv_usec'] / 1000000); 
echo “System time: “. 
($data['ru_stime.tv_sec'] + 
$data['ru_stime.tv_usec'] / 1000000); 
/* prints
User time: 1.088171
System time: 1.675315
*/

// this is relative to the loaded script's path 
// it may cause problems when running scripts from different directories 
require_once(‘config/database.php'); 
// this is always relative to this file's path 
// no matter where it was included from 
require_once(dirname(__FILE__) . ‘/config/database.php');

// some code 
// … 
my_debug(“some debug message”, __LINE__); 
/* 输出
Line 4: some debug message
*/ 
// some more code 
// … 
my_debug(“another debug message”, __LINE__); 
/* 输出
Line 11: another debug message
*/ 
function my_debug($msg, $line) { 
echo “Line $line: $msg\n”;
}
 

// generate unique string 
echo uniqid(); 
/* 输出
4bd67c947233e
*/ 
// generate another unique string 
echo uniqid(); 
/* 输出
4bd67c9472340
*/

// 前缀 
echo uniqid(‘foo_'); 
/* 输出
foo_4bd67d6cd8b8f
*/ 
// 有更多的熵 
echo uniqid(”,true); 
/* 输出
4bd67d6cd8b926.12135106
*/ 
// 都有 
echo uniqid(‘bar_',true); 
/* 输出
bar_4bd67da367b650.43684647
*/

// 一个复杂的数组 
$myvar = array( 
‘hello', 
42, 
array(1,'two'), 
‘apple' 
); 
// 序列化 
$string = serialize($myvar); 
echo $string; 
/* 输出
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”;}
*/ 
// 反序例化 
$newvar = unserialize($string); 
print_r($newvar); 
/* 输出
Array
(
[0] => hello
[1] => 42
[2] => Array
(
[0] => 1
[1] => two
)
[3] => apple
)
*/ 

// a complex array
$myvar = array( 
‘hello', 
42, 
array(1,'two'), 
‘apple' 

); 
// convert to a string 
$string = json_encode($myvar); 
echo $string; 
/* prints
["hello",42,[1,"two"],”apple”]
*/ 
// you can reproduce the original variable 
$newvar = json_decode($string); 
print_r($newvar); 
/* prints
Array
(
[0] => hello
[1] => 42
[2] => Array
(
[0] => 1
[1] => two
)
[3] => apple
)
*/

$string = 
“Lorem ipsum dolor sit amet, consectetur 
adipiscing elit. Nunc ut elit id mi ultricies 
adipiscing. Nulla facilisi. Praesent pulvinar, 
sapien vel feugiat vestibulum, nulla dui pretium orci, 
non ultricies elit lacus quis ante. Lorem ipsum dolor 
sit amet, consectetur adipiscing elit. Aliquam 
pretium ullamcorper urna quis iaculis. Etiam ac massa 
sed turpis tempor luctus. Curabitur sed nibh eu elit 
mollis congue. Praesent ipsum diam, consectetur vitae 
ornare a, aliquam a nunc. In id magna pellentesque 
tellus posuere adipiscing. Sed non mi metus, at lacinia 
augue. Sed magna nisi, ornare in mollis in, mollis 
sed nunc. Etiam at justo in leo congue mollis. 
Nullam in neque eget metus hendrerit scelerisque 
eu non enim. Ut malesuada lacus eu nulla bibendum 
id euismod urna sodales. “; 
$compressed = gzcompress($string); 
echo “Original size: “. strlen($string).”\n”; 
/* 输出原始大小
Original size: 800
*/ 
echo “Compressed size: “. strlen($compressed).”\n”; 
/* 输出压缩后的大小
Compressed size: 418
*/ 
// 解压缩 
$original = gzuncompress($compressed);