----- 017-datetime.php -----
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<html>
<head>
<meta http-equiv="content-type" content="text/html; charset=utf-8">
<title>日期与时间</title>
</head>
<body>
<h3>日期与时间</h3>
<pre>
<?php
$start_time = substr(microtime(), 0, 10);
echo "2014年2月28存在否？", checkdate(2, 28, 2014), "\n";
echo "2014年2月29存在否？", checkdate(2, 29, 2014), "\n";
echo "以数组形式返回当前时间：\n";
print_r(@getdate());//getdate()[0] == time()36*8
echo "现在是：", @date("Y-m-d H:i:s", @getdate()[0]+28800), "\n";
echo "现在的格林威治时间是：", gmdate("Y-m-d H:i:s", @getdate()[0]), "\n";
echo "当前UTC-UNIX时间戳：", time(), "\n";
echo "今天：", @strtotime("TOday"), "\n";
echo "明天：", @strtotime("tomorrow"), "\n";
echo "后天：", @strtotime("tomorrow + 1days"), "\n";
echo "当前UNIX时间戳和微秒数：";
print_r(microtime(false));echo "\n";
echo "当前时间戳浮点数：", microtime(true), "\n";
date_default_timezone_set("PRC");//设置时区为东八区
echo "东八区时间： ", date("Y-m-d H-i-s", time()), "\n";
$end_time = substr(microtime(), 0, 10);
echo "程序开始时间：", $start_time, " ";
echo "程序结束时间：", $end_time, " \n";
printf("程序运行了%f微秒\n", $end_time-$start_time);
?>
</pre>
</body>
</html>
