function in PHP
Advantages Of Function
Function are self
contained block of statement which used to perform any specific task.
—A function is a block
of statements that can be used repeatedly in a program.
—A function will not
execute immediately when a page loads.
—A function will be
executed by a call to the function.
Types of Function:-
—system defined/library/inbuilt
user
definedAdvantages Of Function
—A function is created once but used many times, often from more
than one program.
—It reduces duplication within a
program.
—Debugging and testing a program becomes easier when the
program is subdivide.
How to define Function
A function will be
executed by a call to the function.
Syntax:-
function function_name( )
{
code to be
executed;
}
Note: A function name can start with a letter or
underscore (not a number).
Example:-
<?php
//define function and implements it
function f1()
{
echo
“Hello";
}
//call function whenever you need
f1();
?>
PHP Function Arguments
—Information can be
passed to functions through arguments. An argument is just like a variable.
—Arguments are
specified after the function name, inside the parentheses. You can add as many
arguments as you want, just seperate them with a comma.
<?php
function familyName($fname)
{
echo
"Hello ".$fname."..<br>";
}
familyName("Jani");
familyName("Hege");
?>
PHP Default Argument Value
how to use a default parameter, If we call the function.
<?php
function setHeight($minheight=50) {
echo "The
height is : $minheight <br>";
}
setHeight(350);
setHeight(); // will use the default value of 50
setHeight(135);
setHeight(80);
?>
PHP Functions - Returning values
—To let a function
return a value, use the return statement.
<?php
function sum($x,$y)
{
$z=$x+$y;
return $z;
}
echo "5 + 10 = " . sum(5,10) . "<br>";
echo "7 + 13 = " . sum(7,13) . "<br>";
echo "2 + 4 = " . sum(2,4);
?>
Scope Of Variables
There are 3 types of variables i.e
used inside a function:-
—Local
—Global
—Static
Local Variable
—Local variables are always initialize inside the
function body. Local variable cant work outside function body.
<?php
function add()
{
$x=100;
$y=200;
$sum=$x+$y;
echo "sum of given no=".$sum;
}
add();
?>
Output
: Sum of
given no = 300
Here define a
variable $x and $y . Variable $x and $y has been defined inside add( ) function
so these variables are not accessible outside the add( ) function.
Global Variable
—Global variables are always initialize outside the
function body.
—Global variable work inside the function body as well as
outside function body.
—To access Global variable we have to use global keyword.
<?php
$x=100;
$y=200;
function add()
{
global $x,$y;
$sum=$x+$y;
echo "sum of
given no=".$sum;
}
add();
?>
There are two variables declare $x and $y outside the
function body.
Now if we want to call these global variable $x and $y inside add( ) and sub( ) function
then used “global” keyword before the variable name like “global $x” and “global $y”.
Now if we want to call these global variable $x and $y inside add( ) and sub( ) function
then used “global” keyword before the variable name like “global $x” and “global $y”.
Static Variable
When a function is
completed, all of its variables are normally deleted. However, sometimes you
want a local variable to not be deleted then use static keyword.
<?php
function Test()
{
static $x=0;
echo $x;
$x++;
}
Test();
Test();
Test();
?>
Output : 0 1 2
PHP array
All the variables you have used have held only a single
value.
—Array variables are “special” because they can hold more than one value in one
single variable.
—This makes them particularly useful for storing related
values.
There are three types
of array:-
—Indexed array : An array with a
numeric index
—Associative array : An array where
each key is associated with a value
—Multidimensional array : An array
containing one or more array
—