PHP : $_FILES, $_ENV, $_COOKIE, $_SESSION

Last update on May 28 2022 12:22:07 (UTC/GMT +8 hours)

PHP : $_FILES

Description

$_FILES is a super global variable which can be used to upload files. Here we will see an example in which our php script checks if the form to upload the file is being submitted and generates a message if true.

Here is the html code (upload.php):

<html>
<body>
<form action="upload_file.php" method="post"
enctype="multipart/form-data">
<label for="file">Filename:</label>
<input type="file" name="file" id="file" />
<br />
<input type="submit" name="submit" value="Submit" />
</form>
</body>
</html>

Code of files.php file:

<?php
if ($_FILES["file"] > 0)
  {
  echo "You have selected a file to upload";
  }
?>

PHP: $_ENV

Description

$_ENV is used to return the environment variables from the web server.

<?php
echo $_ENV['username'];
?>

Example of $_ENV

<?php
echo "my username is ".$_ENV['username'];
?>

PHP: $_COOKIE

Description

Cookies are small text files loaded from a server to a client computer storing some information regarding the client computer, so that when the same page from the server is visited by the user, necessary information can be collected from the cookie itself, decreasing the latency to open the page.

$_COOKIE retrieves those cookies.

<?php
setrawcookie();
print_r($_COOKIE);
?>

PHP: $_SESSION

Description

Sessions are wonderful ways to pass variables. All you need to do is start a session by session_start();Then all the variables you store within a $_SESSION, you can access it from anywhere on the server. Here is an example:

Example of $_SESSION

<?php
session_start();
$_SESSION['w3resource']='The largest online tutorial';
echo $_SESSION['w3resource'];
?>

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PHP: Tips of the Day

How to Sort Multi-dimensional Array by Value?

Try a usort, If you are still on PHP 5.2 or earlier, you'll have to define a sorting function first:

Example:

function sortByOrder($a, $b) {
    return $a['order'] - $b['order'];
}

usort($myArray, 'sortByOrder');

Starting in PHP 5.3, you can use an anonymous function:

usort($myArray, function($a, $b) {
    return $a['order'] - $b['order'];
});

And finally with PHP 7 you can use the spaceship operator:

usort($myArray, function($a, $b) {
    return $a['order'] <=> $b['order'];
});

To extend this to multi-dimensional sorting, reference the second/third sorting elements if the first is zero - best explained below. You can also use this for sorting on sub-elements.

usort($myArray, function($a, $b) {
    $retval = $a['order'] <=> $b['order'];
    if ($retval == 0) {
        $retval = $a['suborder'] <=> $b['suborder'];
        if ($retval == 0) {
            $retval = $a['details']['subsuborder'] <=> $b['details']['subsuborder'];
        }
    }
    return $retval;
});

If you need to retain key associations, use uasort() - see comparison of array sorting functions in the manual

Ref : https://bit.ly/3i77vCC