四个PHP非常实用的功能

// 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
)
/

// 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
)
/

$files = glob('../images/a.jpg');
print_r($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\\images\apple.jpg
[1] => C:\wamp\\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
)
/