12.What is Function?

Function is a block of code that it will process and when we called it .
Function has the following advantages :
- Reduction of the same coding
- Easy Error
- Line of Code
- Time
Function is divided into two types :
- Pre-defined Function (Built-in Function)
- Manual Function (User define Function)
Pre-defined Function
- Abs ($ x)
abs ($ x) user Functin for providing absolute value to $ x.
- Round ($ x)
round ($ x) user Functin for only around $ x.
- Ceil ($ x)
ceil ($ x) user Functin for integer values ​​greater than the value of $ x.
- Date (string format, int timestamp)
- d: day
- L: full day
- M: month
- F: full month
- Y: full year
- y:  year
- Time ()
Function used to display the date.
example

echo date("l, F dS , Y",strtotime("2010/12/23"))";

echo date("l , F d , Y H : i : s", time());

Result

Thursday, December 23rd , 2010

Saturday , March 12 , 2011 14 : 30 : 45

Manual Function

1. No Parameter Function
Syntax

function functionName()

{

  statements;

}

Note: - Naming Function is we have to put it is the process of our Function. - Function names begin with letters or _ but we can not start with numbers. How to call funtion

functionName();

example

<?php

 function printWelcome()

 {

   echo "Welcome to www.itkonkhmer.com";

 }

 echo "Hello all visitor";

  printWelcome();

?>

2. Parameter Function
Syntax

function functionName($par1,$par2,...)

{

   statements;

}

How to call function

functionName(($par1,$par2,...);

example

function UserWelcome($name,$id)

{

    echo "Hello " . $name;

    echo "ID : " . $id ;

}

UserWelcome("Visiter","027RT");

Result

Hello Visitor

ID : 027RT

3. Returning Function
Syntax

function functionName($par1,$par2,...)

{

 statements;

 return value;

}

4. Pass by value, pass by reference parameter - Pass by value: Argument is such that it does not provide value to the Parameter value attached to it. - Pass by value: Argument is such that it needs to provide value to the Parameter assigned to it by using signs. Results

After calling function PassByValue a=10

After calling function PassByReference b=21