基本的php表单计算问题

Question

我做的事情可能非常愚蠢，想知道我是否能让任何人指出我做错了什么。教我自己的PHP，并在这样做，我试图制作一个工资计算器。它给了我这些结果：

Your results:
 29 years old earning
$205per day working
$5days a week at a
Your total earned money at age 65 is $0.
While your yearly income is
49200

显然，总赚来的钱数字不正确。 0不对。

这里是完整的代码

<?php

//get the values from the $_POST array

$age = $_POST['age'];
$days = $_POST['days'];
$pay = $_POST['pay'];



//calculate the total:

$howold = 65 - $age;
$retireageincome = $yearlyincome * $howold;
$yearlyincome = $pay * $days * 4 * 12;




//print out results

print "<p>Your results:<br>
<span class=\"number\">$age</span> years old earning <br>
$<span class=\"number\">$pay</span>per day working <br>
$<span class=\"number\">$days</span>days a week at a<br>
Your total earned money at age 65 is $<span class=\"number     
\">$retireageincome</span>.<br>
While your yearly income is <br>
<span class=\"number\">$yearlyincome</span>  </p>";

?>

</body>
</html>

Answer 1

您尝试在$yearlyincome的值已知之前使用$yearlyincome。

命令顺序很重要。移动

$yearlyincome = $pay * $days * 4 * 12;

位于使用$yearlyincome的行之前，您应该看到非0值。