PHP基础：预定义变量

对有编程经验，但新入手web编程的人来说，先熟悉预定义变量的用法是个比较好的方式。

一、学习途径：

PHP手册->语言参考->预定义变量

1. $_POST

把里面的例子做一遍，很有好处。

ex1：

telconstar99 at hotnospampleasemail dot com (20-May-2008 08:49)

<?

//If we submitted the form
if(isset($_POST['submitMe']))
{
     echo("Hello, " . $_POST['name'] . ", we submitted your form!");
}
//If we haven't submitted the form
else
{
?>
    <form action="<?=$_SERVER['PHP_SELF']?>" method="POST">
    <input type="text" name="name"><br>
    <input type="submit" value="submit" name="submitMe">
    </form>
<?
}
?>

 1个知识点：

(1) 第12行，$_SERVER['PHP_SELF']，表示当前执行脚本的文件名，如test.php。

可见，先熟悉掌握预定义变量很有用。

 ex2：

php dot net at bigbadaboom dot net (15-Jul-2008 04:06)

<input type="submit" name="submit">

isset($_POST["submit"]) returns false

<input type="submit" name="submit" value="Next">

isset($_POST["submit"]) returns true.

This might seem obvious for text buttons since they need a label anyway.  However, if you are using image buttons, it might not occur to you that you need to set a value attribute as well.  For example, the value attribute is required in the following element if you want to be able to detect it in your script.

<input type="image" name="submit" src="next.gif" value="Next"> 

一个知识点：

如果在input里遗漏value的值，$_POST["submit"]将为null。

写程序是个细心的经验活，今天根据手册做了几个例子，对基本知识点有了更清楚的认识。有收获。