推荐9个常用的php代码（记得收藏）

min(max($a, 1), 12);

$date = '2016-2-29';

list($year, $month, $day) = explode('-', $date);

echo checkdate($month, $day, $year) ? 'yes' : 'no';

$a = 'long_under_line_name';

echo lcfirst(str_replace('_', '', ucwords($a, '_')));

$a = 'longCamelCaseName';

echo strtolower(preg_replace('/[A-Z]/', '_$0', $a));

$link = new mysqli('127.0.0.1', '用户名', '密码', '数据库名');

$link->query('SET NAMES utf8');

$rs = $link->query('SELECT * FROM table');

while ($row = $rs->fetch_assoc()) {

    // $row为查出的每一行

}

$link->close();

echo $_SERVER['REMOTE_ADDR'];

$dict = ['零', '一','二','三','四','五','六','七','八','九','十','百','千','万','亿'];

$num = 1234567890;

$string = strrev($num);

$text = '';

for ($i = 0; $i !== 12; $i += 4) {

    $s = substr($string, $i, 4);

    $t = '';

    for ($j = 0; $j != 4; $j++) {

        if (!isset($s[$j])) continue;

        $u = $j && $s[$j] ? $dict[9 + $j] : '';

        $t = (($t || $s[$j]) && ($s[$j] !== '1' || $j !== 1) ? $dict[$s[$j]] : '') . $u . $t;

    }

    if ($t) {

        $text = preg_replace('/零+/u', '零', $t) . ($i ? $dict[12+$i/4]: '') . $text;

    }

}

echo $text . PHP_EOL;

$str = 'false';

$bool = filter_var($str, FILTER_VALIDATE_BOOLEAN);

// 两种方式

echo php_uname();

// Windows 输出 Windows NT PC115080 6.1 build 7601 (Windows 7 Professional Edition Service Pack 1) AMD64

// Linux 输出 Linux VM_238_239_centos 3.10.0-514.21.1.el7.x86_64 #1 SMP Thu May 25 17:04:51 UTC 2017 x86_64

echo PHP_OS;

// Windows 输出 WINNT

// Linux 输出 Linux