JSON stands for JavaScript Object Notation, and is a syntax for storing and exchanging data.
Since the JSON format is a text-based format, it can easily be sent to and from a server, and used as a data format by any programming language.
A callback function (often referred to as just “callback”) is a function which is passed as an argument into another function.
Any existing function can be used as a callback function. To use a function as a callback function, pass a string containing the name of the function as the argument of another function: Continue reading PHP Callback Functions
The following example uses the filter_var() function to check if a variable is both of type INT, and between 1 and 200:
<?php
$int = 122;
$min = 1;
$max = 200;
if (filter_var($int, FILTER_VALIDATE_INT, array("options" => array("min_range"=>$min, "max_range"=>$max))) === false) {
echo("Variable value is not within the legal range");
} else {
echo("Variable value is within the legal range");
}
?>
Validating data = Determine if the data is in proper form.
Sanitizing data = Remove any illegal character from the data. Continue reading PHP Filters
A session is a way to store information (in variables) to be used across multiple pages.
Unlike a cookie, the information is not stored on the users computer. Continue reading PHP Sessions
A cookie is often used to identify a user. A cookie is a small file that the server embeds on the user’s computer. Each time the same computer requests a page with a browser, it will send the cookie too. With PHP, you can both create and retrieve cookie values.
With PHP, it is easy to upload files to the server.
However, with ease comes danger, so always be careful when allowing file uploads!
First, ensure that PHP is configured to allow file uploads.
In your “php.ini” file, search for the file_uploads directive, and set it to On:
file_uploads = On
In this chapter we will teach you how to create and write to a file on the server.
The fopen() function is also used to create a file. Maybe a little confusing, but in PHP, a file is created using the same function used to open files.
If you use fopen() on a file that does not exist, it will create it, given that the file is opened for writing (w) or appending (a). Continue reading PHP File Create/Write
In this chapter we will teach you how to open, read, and close a file on the server.
A better method to open files is with the fopen() function. This function gives you more options than the readfile() function. Continue reading PHP File Open/Read/Close
File handling is an important part of any web application. You often need to open and process a file for different tasks.
PHP has several functions for creating, reading, uploading, and editing files.
Be careful when manipulating files!
When you are manipulating files you must be very careful.You can do a lot of damage if you do something wrong. Common errors are: editing the wrong file, filling a hard-drive with garbage data, and deleting the content of a file by accident.