- PHP is a recursive acronym for "Hypertext Preprocessor".
- PHP is a widely-used, open source scripting language.
- PHP scripts are executed on the server.
- PHP costs nothing, it is free to download and use.
- PHP files can contain text, HTML, CSS, JavaScript, and PHP code.
- PHP code are executed on the server, and the result is returned to the browser as plain HTML.
- PHP files have extension ".php".
- PHP can generate dynamic page content.
- PHP can create, open, read, write, delete, and close files on the server.
- PHP can collect form data.
- PHP can send and receive cookies.
- PHP can add, delete, modify data in your database.
- PHP can restrict users to access some pages on your website.
- PHP can encrypt data.
- PHP runs on various platforms (Windows, Linux, Unix, Mac OS X, etc.).
- PHP is compatible with almost all servers used today (Apache, IIS, etc.).
- PHP supports a wide range of databases.
- PHP is easy to learn and runs efficiently on the server side.
- With PHP you are not limited to output HTML. You can output images, PDF files, and even Flash movies.
- You can also output any text, such as XHTML and XML.
- In PHP, all user-defined functions, classes, and keywords (e.g. if, else, while, echo, etc.) are NOT case-sensitive.However; in PHP, all variables are case-sensitive.
- PHP is a Loosely Typed Language.PHP automatically converts the variable to the correct data type, depending on its value.In other languages such as C, C++, and Java, the programmer must declare the name and type of the variable before using it.
PHP Variables:-
As with algebra, PHP variables can be used to hold values (x=5) or expressions (z=x+y).
A variable can have a short name (like x and y) or a more descriptive name (age, carname, total_volume).
Rules for PHP variables:
- A variable starts with the $ sign, followed by the name of the variable
- A variable name must start with a letter or the underscore character
- A variable name cannot start with a number
- A variable name can only contain alpha-numeric characters and underscores (A-z, 0-9, and _ )
- Variable names are case sensitive ($y and $Y are two different variables)
PHP Variables Scope:-
In PHP, variables can be declared anywhere in the script.
The scope of a variable is the part of the script where the variable can be referenced/used.
PHP has three different variable scopes:
- local
- global
- static
PHP Data Types:-
PHP Integers:
An integer is a number without decimals.
Rules for integers:
- An integer must have at least one digit (0-9)
- An integer cannot contain comma or blanks
- An integer must not have a decimal point
- An integer can be either positive or negative
- Integers can be specified in three formats: decimal (10-based), hexadecimal (16-based - prefixed with 0x) or octal (8-based - prefixed with 0)
Example
<?php
$x = 5985;
var_dump($x);
echo "<br>";
$x = -345; // negative number
var_dump($x);
echo "<br>";
$x = 0x8C; // hexadecimal number
var_dump($x);
echo "<br>";
$x = 047; // octal number
var_dump($x);
?>
Basic PHP Syntax:-
A PHP script can be placed anywhere in the document.
A PHP script starts with <?php and ends with ?>
Example:
<!DOCTYPE html>
<html>
<body>
<h1>My first PHP page</h1>
<?php
echo "Hello World!";
?>
</body>
</html>
PHP statements are terminated by semicolon (;).
The closing tag of a block of PHP code also automatically implies a semicolon.
So you do not have to have a semicolon terminating the last line of a PHP block.
