-----------------index.html----------------------------------------
<head>
<title>日期计算</title>
</head>
<p>日期计算</p>
<form method="POST" action="date.php">
年：<input type="text" name="year" maxlength="30" size="30"></br></br>
月：<input type="text" name="month" maxlength="30" size="30"></br></br>
日：<input type="text" name="date" maxlength="30" size="30"></br></br>
<input type="submit" value="计算">
</form>
-----------------------date.php----------------------------------------------
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
</head>
<body>
<?php
$year = $_POST['year'];
$month = $_POST['month'];
$date = $_POST['date'];
$begin = "$year-$month-$date";
echo "开始（放假）日期: $begin <br><br>";
$begintime = strtotime($begin);
$endtime = $begintime + (178 * 24 * 3600); #目前产检天数标准为178天
$end = date("Y-m-d", $endtime);
echo "结束（上班）日期: $end <br><br>";
?>
</body>
</html>