One minute to figure out what are predefined variables in php? What is the $_POST variable?

We have learned so much about PHP. Today we will learn in one minute what are predefined variables in PHP? What is the $_POST variable? , I wonder if you have fully mastered it. If not, then follow this article to continue learning

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Predefined variables:

The so-called predefined variables actually refer to variables that are predefined in the language tool PHP;

We just "enjoy it and use it"

Overview:

Mainly include:$, _GET,S_ POST,$_ REQUEST, $ _ SERVER, $GLOBALS,

• ## are all arrays

• system definition and maintenance - that is, we should not assign values ​​​​to them or To destroy its value, you should only "use its value"

• has a super-global scope and can be used anywhere.

• May have different values ​​in different situations

$_POST variable:

Meaning:

It represents all the data submitted when the user submits through the form in post mode (methodu "post") - this is called post data.

<!--
以下表单的数据，点击提交后，会将所有表单数据提交给
8post_ _data.php这个页面(文件)，并在该文件中去处理
其实就是指:程序进入该文件中运行。
=-》
<form action="8post data. php" method="post">
数据1: <input type="text" name="data1 />
<br />
数据2: <input type="text" name= "data2" />
<br />
<input type="submit" value="提交" />
</form>

The code is as follows:

$post_data php page and output results:

<?php
//先一个一个获取数据:
$d1 = $_POST[&#39;datal&#39;];
$d2 = $POST[ &#39;data2&#39;];
//然后输出，看看:
echo "d1 = $d1, d2 = $d2";
echo "<hr />";
//再来看看整个$_ POST这个数组数据!
print_r($_POST);
?>

The running results are as follows:

ise (variable):

Determine whether the variable exists or whether the variable is empty (nul); if it exists, it is true, otherwise It is false

empty (variable): Determine whether the "inner core" of the variable is empty (not null, but empty). Basically, it is some rigid rules. The following data are all "empty" ": ."" "0", false, null, array0The empty array is also empty

If the content of a variable is empty, the result returned by empty(0 is true, otherwise it is false;

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PHP Video Tutorial"

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