Rizwan Abbasi’s Blog











{مارچ 10, 2006}   First Lecture

A PHP file may contain text, HTML tags and scripts. Scripts in a PHP file are executed on the server. 


What you should already know  

Before you continue you should have some basic understanding of the following: 

  • WWW, HTML and the basics of building Web pages 
  • Some scripting knowledge 

If you want to study these subjects, go to our Home Page 


What is PHP?  

  • PHP stands for PHP: Hypertext Preprocessor 
  • PHP is a server-side scripting language, like ASP 
  • PHP scripts are executed on the server 
  • PHP supports many databases (MySQL, Informix, Oracle, Sybase, Solid, PostgreSQL, Generic ODBC, etc.) 
  • PHP is an open source software (OSS) 
  • PHP is free to download and use 

What is a PHP File?  

  • PHP files may contain text, HTML tags and scripts 
  • PHP files are returned to the browser as plain HTML  
  • PHP files have a file extension of ".php”, ".php3”, or ".phtml” 

What is MySQL?  

  • MySQL is a small database server 
  • MySQL is ideal for small and medium applications 
  • MySQL supports standard SQL 
  • MySQL compiles on a number of platforms 
  • MySQL is free to download and use 

PHP + MySQL  

  • PHP combined with MySQL are cross-platform (means that you can develop in Windows and serve on a Unix platform) 

Why PHP?  

  • PHP runs on different platforms (Windows, Linux, Unix, etc.) 
  • PHP is compatible with almost all servers used today (Apache, IIS, etc.) 
  • PHP is FREE to download from the official PHP resource: www.php.net 
  • PHP is easy to learn and runs efficiently on the server side 

Where to Start?  

  • Install an Apache server on a Windows or Linux machine 
  • Install PHP on a Windows or Linux machine 
  • Install MySQL on a Windows or Linux machine 


{مارچ 5, 2006}   4th Lecture.

Operators are used to operate on values.


PHP Operators

This section lists the different operators used in PHP.
Arithmetic Operators

Operator
Description
Example
Result
+ Addition x=2
x+2
4
Subtraction x=2
5-x
3
* Multiplication x=4
x*5
20
/ Division 15/5
5/2
3
2.5
% Modulus (division remainder) 5%2
10%8
10%2
1
2
0
++ Increment x=5
x++
x=6
Decrement x=5
x–
x=4

Assignment Operators

Operator
Example
Is The Same As
= x=y x=y
+= x+=y x=x+y
-= x-=y x=x-y
*= x*=y x=x*y
/= x/=y x=x/y
%= x%=y x=x%y

Comparison Operators

Operator
Description
Example
== is equal to 5==8 returns false
!= is not equal 5!=8 returns true
> is greater than 5>8 returns false
  is less than 5
>= is greater than or equal to 5>=8 returns false
  is less than or equal to 5

Logical Operators

Operator
Description
Example
&& and x=6
y=3
(x 1) returns true
|| or x=6
y=3
(x==5 || y==5) returns false
! not x=6
y=3
!(x==y) returns true


{مارچ 5, 2006}   5th Lecture

Conditional statements in PHP are used to perform different actions based on different conditions.


Conditional Statements

Very often when you write code, you want to perform different actions for different decisions. You can use conditional statements in your code to do this.
In PHP we have two conditional statements:

  • if (…else) statement – use this statement if you want to execute a set of code when a condition is true (and another if the condition is not true)
  • switch statement – use this statement if you want to select one of many sets of lines to execute

The If Statement

If you want to execute some code if a condition is true and another code if a condition is false, use the if….else statement.

Syntax

if (condition) 
code to be executed if condition is true; 
else 
code to be executed if condition is false; 

Example

The following example will output "Have a nice weekend!” if the current day is Friday, otherwise it will output "Have a nice day!”:

 
 

$d=date("D"); 
if ($d=="Fri") 
echo "Have a nice weekend!"; 
else 
echo "Have a nice day!"; 
?> 
 
 

If more than one line should be executed when a condition is true, the lines should be enclosed within curly braces:

 
 

$x=10; 
if ($x==10) 
{ 
echo "Hello "; 
echo "Good morning "; 
} 
?> 
 
 


The Switch Statement

If you want to select one of many blocks of code to be executed, use the Switch statement.

Syntax

switch (expression) 
{ 
case label1: 
  code to be executed if expression = label1; 
  break;  
case label2: 
  code to be executed if expression = label2; 
  break; 
default: 
  code to be executed 
  if expression is different 
  from both label1 and label2; 
} 

Example

This is how it works: First we have a single expression (most often a variable), that is evaluated once. The value of the expression is then compared with the values for each case in the structure. If there is a match, the block of code associated with that case is executed. Use break to prevent the code from running into the next case automatically. The default statement is used if none of the cases are true.

 
 

switch ($x) 
{ 
case 1: 
  echo "Number 1"; 
  break; 
case 2: 
  echo "Number 2"; 
  break; 
case 3: 
  echo "Number 3"; 
  break; 
default: 
  echo "No number between 1 and 3"; 
} 
?> 
 
 



{مارچ 1, 2006}   Rizwan Abbasi

I am Rizwan Abbasi. Today is 2nd of March 2006. It’s 01:27AM. I am learning now SQL (Structured Query Language) and also talking to Fahdi.



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