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Origins and Uses of PHP
- Origins
- Rasmus Lerdorf - 1994
- Developed to allow him to track visitors to his Web site
- PHP is an open-source product
- PHP was originally an acronym for Personal Home Page, but later it became PHP: Hypertext Preprocessor
- PHP is used for form handling, file processing, and database access
PHP is a widely-used general-purpose scripting language that is especially suited for Web development and can be embedded into HTML.
Overview of PHP
- PHP is a server-side scripting language whose scripts are embedded in HTML documents - Similar to JavaScript, but on the server side
- PHP syntax is similar to that of JavaScript
For a browser read and interpret the PHP commands, the file must be have an extension .PHP
EXAMPLE - before myPage.html- now myPage.php
More at http://www.w3schools.com/php/php_intro.asp
General Syntactic Characteristics
- PHP code can be specified in an HTML document internally or externally:
Internally: <?php .......php code goes here......... ?>
Externally: include ("myScript.inc")
- the file can have both PHP and HTML
- Comments - three different kinds // ... # ... /* ... */
- Output from a PHP script is HTML that is sent to the browser.
- PHP code is placed in the body of an HTML document
A little bit of “Programming”
-It is the process of designing, writing, testing, debugging, and maintaining the source code of computer programs.
- This source code is written in a programming language.
- The code may be a modification of an existing source or something completely new.
- The purpose of programming is to create a program that exhibits a certain desired behavior (customization).
A little bit of “Programming” (continue)
-The details look different in different languages, but a few basic instructions appear in just about every language:
- input: Get data from the keyboard, a file, or some other device.
- output: Display data on the screen or send data to a file or other device.
- arithmetic: Perform basic arithmetical operations like addition and multiplication.
- conditional execution: Check for certain conditions and execute the appropriate sequence of statements.
- repetition: Perform some action repeatedly, usually with some variation.
THE program languages such as PHP, JAVA, C, JAVASCRIPT, ... Implement these instructions though commands.
Usually each program language has its own syntax.
PHP –> VARIABLE
Variables are used for storing values, like text strings, numbers or arrays.
When a variable is declared, it can be used over and over again in your script.
All variables in PHP start with a $ sign symbol.
Example
$var_name = value;
<?php $txt="Hello World!"; // this a string being assigned to a variable $x=16; // this a number being assigned to a variable ?>
http://en.wikipedia.org/wiki/Variable_%28programming%29
http://www.w3schools.com/php/php_variables.asp
PHP –> Control Statements
- Relational operators - same as JavaScript, (including === and !==)
- Boolean operators – “OR” and “AND”
- Selection statements - if, if-else, elseif
- HTML can be intermingled with PHP script
<?php $a = 7; $b = 7; if ($a == $b) { $a = 3 * $a; } ?>
User-Defined Functions
- Syntactic form:
function function_name(formal_parameters) { … }
- General Characteristics
- Functions need not be defined before they are called
- The return function is used to return a value; - If there is no return, there is no returned value
EXAMPLE
function set_max(&$max, $first, $second) { if ($first >= $second) $max = $first; else $max = $second; }
PHP –> COMMANDS - > ECHO
PHP has a number of predefined functions ready use.
• Echo () PHP Function - is used to output the given argument.
<?php Echo "Hello"; //Outputs a string
Echo $variable; //Outputs a variable
Echo "Multiple things " . $on . " one line"; //Outputs a string, then a variable, then a string. All are separated with a [.] period
?>
PHP –> COMMANDS -> MAIL
PHP has a number of predefined functions ready use.
• Mail () PHP Function - is used to send an email.
mail ($to, $subject, $message, $headers) // headers are optional
<?php$to = '[email protected]';$subject = 'the subject';$message = 'hello';$headers = 'From: [email protected]' . "\r\n" . 'Reply-To: [email protected]' . "\r\n" . mail($to, $subject, $message, $headers);
?>
