1.表单post过来的是字符串类型么？
2.如果是字符串类型，那么下面这段怎么解释，为何不经过类型转换就可以直接相加？Python可不是这样的哦
<html><?php// create short variable names $tireqty = $_POST['tireqty']; $oilqty = $_POST['oilqty']; $sparkqty = $_POST['sparkqty']; // create constant names define ('TIREPRICE',100); define ('OILPRICE',10); define ('SPARKPRICE',4);?> <head> <title>Bob's Auto Parts - Order Result</title> </head> <body> <h1>Bob's Auto Parts</h1> <h2>Order Results</h2> <?php //echo '<p>Order processed.</p>'; echo '<p>Order processed at '.date('H:i , jS F Y').'</p>'; // overcome not integer number if (is_string($tireqty) == True or is_string($oilqty) == True or is_string($sparkqty) == True) { echo "one of your input is type string.<br/>"; echo '<p>Your order is as follow: </p>'; echo $tireqty. ' tires. <br/>'; echo $oilqty. ' bottles of oil<br/>'; echo $sparkqty. ' spark plugs<br/>'; // calc total items ordered $totalqty = 0; $totalqty = $tireqty + $oilqty + $sparkqty; if ($totalqty == 0) { echo 'You did not order anything on the previous page!<br/>'; } else { echo "Items ordered: $totalqty <br/>"; // calc total amount $toatlamount = 0; $toatlamount = $tireqty * TIREPRICE + $oilqty * OILPRICE + $sparkqty * SPARKPRICE; echo 'Subtotal: $'.number_format($toatlamount,2).'<br/>'; // calc total tax $taxrate = 0.10; $totaltaxrate = 0; $totaltaxrate = $toatlamount * 0.10; echo 'Total tax: $'.number_format($totaltaxrate,2).'<br/>'; } } ?> </body></html>Bob's Auto PartsOrder ResultsOrder processed at 17:33 , 15th April 2013one of your input is type string.Your order is as follow: 1 tires. 2 bottles of oil3 spark plugsItems ordered: 6 Subtotal: $132.00Total tax: $13.20
python的字符串连接符和算数相加都是+号，如果你 '1'+'2'， python没法明白你的意思，到底相加还是相连？它可不能自作主张，只好严格按类型运算。
但PHP的字符串连接符是 . 号，如果你用 '1'+'2'; 它当然明白你是想相加，而不是相连。因此结果自然是3，而不是'12'。甚至你用 '1'+'ssss' 也会得到数字1
1. 是字符串类型。
2. 有很多语言有自动Cast的功能的。
呵呵呵 刚开始接触弱类型语言的时候都有这类想发，习惯就好了...
python是弱类型，是不需要声明字段属性的，python虽然是弱类型，但是不会将字段类型默认识别。
传递是什么类型就还是什么类型
