What are the global arrays of php receiving values?

PHP is a high-level programming language that can operate and process data by receiving input values. In PHP, there are many global arrays that can be used to receive input values. This article will introduce global arrays commonly used in PHP and discuss their characteristics and usage.

1. $_GET

$_GET is a super global variable of PHP, used to receive the parameters of the HTTP GET request. HTTP GET request is a request method used to obtain resources from the server. These request parameters are passed to the server in the form of key-value pairs. When the form is submitted using the get method, the data in the form will be automatically added to the $_GET array. For example:

Name: <input type="text" name="name"><br>
E-mail: <input type="text" name="email"><br>
<input type="submit">

When submitting the form, PHP will Add key-value pairs in the $_GET array, as follows:

Array
(

[name] => John
[email] => john@example.com

)

When getting parameters in the $_GET array, you can use The following code:

$name = $_GET['name'];
$email = $_GET['email'];

It should be noted that the $_GET array All key-value pairs are of string type.

2. $_POST

$_POST is another super global variable of PHP, used to receive parameters of HTTP POST request. HTTP POST request is also a request method, used to submit data to the server for reception. Compared with $_GET, the request parameters sent by $_POST are not exposed in the URL address bar. When the form is submitted using the post method, the data in the form will be automatically added to the $_POST array. For example:

Name: <input type="text" name="name"><br>
E-mail: <input type="text" name="email"><br>
<input type="submit">

When submitting the form, PHP will Add key-value pairs in the $_POST array, as follows:

Array
(

[name] => John
[email] => john@example.com

)

When getting the parameters in the $_POST array, you can use The following code:

$name = $_POST['name'];
$email = $_POST['email'];

Compared with $_GET, $_POST is more Safe because the parameters are not exposed in the address bar, but it is slower than $_GET.

3. $_FILES

$_FILES is also a super global variable of PHP, used to receive file uploads from HTTP POST requests. The file to be uploaded can be sent to the server through an HTTP POST request. When using a file upload form, the data in the form is automatically added to the $_FILES array. For example:

Select image to upload:
<input type="file" name="fileToUpload" id="fileToUpload">
<input type="submit" value="Upload Image" name="submit">

When you submit the form and select a file to upload, PHP adds attributes to the $_FILES array as follows:

Array
(

[fileToUpload] => Array
    (
        [name] => example.jpg
        [type] => image/jpeg
        [tmp_name] => /tmp/phpVJcax8
        [error] => 0
        [size] => 69130
    )

)

When getting uploaded files, you can use the following code:

$target_dir = "uploads/";
$target_file = $target_dir . basename($_FILES"fileToUpload");
move_uploaded_file ($_FILES["fileToUpload"]["tmp_name"], $target_file);

It should be noted that the uploaded file will be saved to the folder specified by the server.

4. $_COOKIE

$_COOKIE is a super global variable in PHP that is used to receive cookie values ​​stored on the client computer. A cookie is a small text file that is stored on the client computer and used for data interaction with the server. In PHP, you can use the setcookie() function to set cookie values. When a cookie is set, the $_COOKIE array can be used to receive the cookie value. For example:

setcookie("user", "John Doe", time() 3600, "/"); // Set cookie
echo $_COOKIE["user"]; // Output cookie value

In the above code, the setcookie() function sets a cookie named "user" with a value of "John Doe" and expires one hour after the set time. In the echo statement, the $_COOKIE array receives the value of the cookie named "user" and outputs the value.

It should be noted that when using the $_COOKIE array to obtain the cookie value, you do not need to quote the cookie name.

5. $_SESSION

$_SESSION is also a super global variable in PHP, used to store session data. Session data is a more secure way of storing data than cookies. When using the $_SESSION variable, the data is stored on the server side rather than on the client machine. In PHP, a session can be started through the session_start() function. For example:

session_start();
$_SESSION["favcolor"] = "green";
$_SESSION["favanimal"] = "cat";
echo "Session variables are set.";

In the above code, the session_start() function starts a session and stores two values ​​​​through the $_SESSION["favcolor"] and $_SESSION["favanimal"] variables. In the output statement, the $_SESSION array receives the values ​​of the two variables and outputs them.

It should be noted that when using the $_SESSION array to obtain session data, you need to use the session_start() function in the script to start the session.

Summarize:

In PHP, you can use five global arrays: $_GET, $_POST, $_FILES, $_COOKIE and $_SESSION to receive data submitted from the client. Using these global arrays, you can easily obtain the data submitted by the client and perform various data processing operations. When using global arrays, you need to pay attention to the case of variable names and data type conversion.

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