JavaScript by A. Sadat

Information in this document came from PHP Manual and the  Introductory Tutorial.

What is Server Side Scripting?

A tool that lets you create dynamic web pages. Sripting languages such as PHP, associated with the Apache Web Server and VB Script, associated with Microsoft's Internet Information Server allow the mixing of HTML and the scripting language in the same file. This methodology differs from compiled CGI programs. You can write executables in C, C++, Visual Basic that can create Dynamic Web pages, but the HTML has to be embedded in the code. Web pages created with scripting languages are treated just like regular HTML pages, you can create and edit them the same way you normally create regular HTML pages.

Why study PHP?

Since we have access to an Apache Web Server with the PHP Parser, we will examine the use of PHP to create Dynamic Web Pages. PHP (recursive acronym for "PHP: Hypertext Preprocessor") is a widely-used Open Source general-purpose scripting language that is especially suited for Web development and can be embedded into HTML. 
<html>
    <head>
        <title>Hello World</title>
    </head>
    <body>
        <?php 
        echo "Hello World"; 
        ?>
    </body>
</html>
The PHP code is enclosed in special start <?php and end ?> tags that allow you to jump into and out of "PHP mode".

Escaping from HTML

When PHP parses a file, it simply passes the text of the file through until it encounters one of the special tags which tell it to start interpreting the text as PHP code. The parser then executes all the code it finds, up until it runs into a PHP closing tag, which tells the parser to just start passing the text through again. This is the mechanism which allows you to embed PHP code inside HTML: everything outside the PHP tags is left utterly alone, while everything inside is parsed as code.

Enought to get started

Instruction Separation

Instructions are separated by the ;

Comments

Supports C, C++ and Unix Shell type comments 
         
<?php echo "A comment follows"; // One-line c++ style comment
/* This is a multi line
   comment multiline comments span more than one line*/ 
echo "Line 1";
// # can be used to place comments at end of line
echo "Line 2"; # This is shell-style style comment
?>

Data Types

Varaiables


<?php
// can use single quotes for string and use ' in string by escaping \'
$str = Stan\'s test'; 
echo $str;
// can use double quotes for strings       
echo "<br>";
// can use "" quotes for string and use " in string by escaping \"
$str1 = "Stan said: \"try this\""; 
echo $str1;
echo "<br>";
$test_1 = 3.45;
echo $test_1;
$_intcntr = 3;
echo $_intcntr;
// can initialize array element by giving array name and inder in square brackets
$ar[0] = "Stan";
$ar[1] = "Mary";
$ar[2] = "Kathy";
// can print an array one element element at a time
for($i=0;$i<3;$i++)
{
   echo $ar[$i];
   echo "<br>";
}
?>

Processing the Data Returned from Form

PHP can access the values returned in the form's fields.  PHP creates a variable with same same name as the input tag's name.  In the form below, the value entered into the text box with name "first" will be contained in a variable called $first, the text box called "last" will have its value returned in a variable called $last.  The echo function can be used to print the value contained in the variable holding the value returned by the form.

Sample Form


<html>
<body>
<form method="post" action="process.php" id=form1 name=form1>
First name:<input type="Text" name="first"><br>
Last name:<input type="Text" name="last"><br>
Address:<input type="Text" name="address"><br>
Position:<input type="Text" name="position"><br>
<input type="Submit" name="submit" value="Enter information">
</form>
</body>
</html>

PHP file to process above form

<html>
<body>
<?php
echo "first=$first<br>"; 
echo "last=$last<br>"; 
echo "addresst=$address<br>"; 
echo "position=$position<br>"; 
?>
</body>
</html>

PHP file to process any form

HTTP_POST_VARS is an array of all the fieldname, value pairs returned by the form and exposed by PHP. The each function returns the current key and value pair from the array $HTTP_POST_VARS and advances the array cursor. If the internal pointer for the array points past the end of the array contents, each() returns FALSE. List() is a language construct that is used to assign a list of variables in one operation. In this case, the fieldname, value pair returned by the each() function is assigned to $name and $value . 

<html>
<body>
<?php
while (list($name, $value) = each($HTTP_POST_VARS)) {
  echo "$name = $value<br>\n";
}
?>
</body>
</html>