PHP FUNCTIONS AND ARRAY.pptx

PHP FUNCTIONS & ARRAYS
Dr.R.Shalini M.Sc.,MPhil.,PhD.,
Assistant Professor
VISTAS

PHP FUNCTIONS
Definition :
PHP function is a piece of code that can be reused many times. It can take input as
argument list and return value. There are thousands of built-in functions in PHP.
Advantage of PHP Functions
 Code Reusability: PHP functions are defined only once and can be invoked many
times, like in other programming languages.
 Less Code: By the use of function, one can write the logic only once and reuse it.
 Easy to understand: PHP functions separate the programming logic. So it is easier to
understand the flow of the application because every logic is divided in the form of
functions.

Two major types of functions:
1.Built-in functions:
These functions are already coded and stored in form of functions.
Example: var_dump, fopen(), print_r(), gettype() and so on.
2.User Defined Functions:
PHP allows to create own customized functions called the user-defined functions.
While creating a user defined function few things to be considered are
Any name ending with an open and closed parenthesis is a function.
A function name always begins with the keyword function.
To call a function we just need to write its name followed by the parenthesis
A function name cannot start with a number. It can start with an alphabet or underscore.
A function name is not case-sensitive.

• A user-defined function declaration starts with the word function:
Syntax
function functionName()
{
code to be executed;
}
Example: 1
<?php
function writeMsg()
{
echo "Hello world!";
}
writeMsg(); // call the function
?>
Output : Hello world

Explanation for the above program :
we create a function named "writeMsg()".
The opening curly brace ( { ) indicates the beginning of the function code, and the closing curly brace (
} ) indicates the end of the function.
The function outputs "Hello world!".
To call the function, just write its name followed by brackets ():
Example: 2
<?php
function addFunction($num1, $num2)
{
$sum = $num1 + $num2;
echo "Sum of the two numbers is : $sum";
}
addFunction(10, 20);
?>
Output: Sum of the two numbers is : 30

PHP Function Arguments
Information can be passed to functions through arguments which is separated by
comma.
It is just like a variable and are specified after the function name, inside the
parentheses. One can add as many arguments as wanted.
Example: 1
<?php
function sayHello($name)
{
echo "Hello $name "; Output:
}
sayHello("Sonoo");
sayHello("Vimal");
sayHello("John");
?>
Hello Sonoo
Hello Vimal
Hello John

Example 1 Program Explanation
The following example has a function with one argument ($name).
When the sayhello() function is called, we also pass along a name (e.g. sonoo),
And the name is used inside the function, which outputs several different names.
Example: 2 Function with two arguments
<?php
function sayHello($name,$age)
{
echo "Hello $name, you are $age years old ";
}
sayHello("Sonoo",27); output:
sayHello("Vimal",29); Hello Sonoo, you are 27 years old
sayHello("John",23);
?> Hello Vimal, you are 29 years old
Hello John, you are 23 years old

PHP Functions - Returning Value
Functions can also return values to the part of program from where it is called.
The return keyword is used to return value back to the part of program, from where it was
called.
The returning value may be of any type including the arrays and objects.
 The return statement also marks the end of the function and stops the execution after that
and returns the value.
Example:
<?php
function circle($r)
{ output
return 3.14*$r*$r;
}
echo "Area of circle is: ".circle(3);
?>

Parameter passing to Functions
PHP allows us two ways in which an argument can be passed into
a function:
 Pass by Value: On passing arguments using pass by value, the value of
the argument gets changed within a function, but the original value
outside the function remains unchanged. That means a duplicate of the
original value is passed as an argument.
Pass by Reference: On passing arguments as pass by reference, the
original value is passed. Therefore, the original value gets altered. In pass
by reference we actually pass the address of the value, where it is stored
using ampersand sign(&).

<?php
// pass by value
function valfun($num)
{
$num += 2;
return $num;
}
// pass by reference
function reffun(&$num)
{
$num += 10;
return $num;
}
$n = 10;
val($n);
echo "The original value is still $n n";
ref($n);
echo "The original value changes to $n";
?>
Output:
The original value is still 10
The original value changes to 20

Definition:
An array is a data structure that stores one or more similar type of values in a single value.
An array is created using an array( ) function.
//create an empty array:
$arr = array();
//create an array with elements 10, 20, 30:
$arr = array(10, 20, 30);
//create an array with mixed types:
$arr = array(10, 3.14, "Hello");
//get the first element:
$x = $arr[0]; //x has value 10
PHP - Arrays

In PHP, there are three types of arrays:
1. Indexed arrays - Arrays with a numeric index
2. Associative arrays - Arrays with named keys
3. Multidimensional arrays - Arrays containing one or more arrays

Numeric array
 PHP index is represented by number which starts from 0.
 We can store number, string and object in the PHP array.
 All PHP array elements are assigned to an index number by default.
There are two ways to define indexed array:
1st way:
$season=array("summer","winter","spring","autumn");
2nd way:
$season[0]="summer";
$season[1]="winter";
$season[2]="spring";
$season[3]="autumn";

Example1
<?php
$season=array("summer","winter","spring","autumn");
echo "Season are: $season[0], $season[1], $season[2] and
$season[3]";
?>
Output:
Season are: summer, winter, spring and autumn

Example:2
<?php
$season[0]="summer";
$season[1]="winter";
$season[2]="spring";
$season[3]="autumn";
echo "Season are: $season[0], $season[1], $season[2]
and $season[3]";
?>
Output:
Season are: summer, winter, spring and autumn

Associative array
An array with strings as index.
This stores element values in association with key values rather than in a
strict linear index order.
Syntax for associative arrays:
array(key=>value,key=>value,key=>value,etc.)
Parameter Description
key Specifies the key (numeric or string)
value Specifies the value

We can associate name with each array elements in PHP using => symbol.
There are two ways to define associative array:
1st way:
$salary=array("Sonoo"=>"350000","John"=>"450000","Kartik"=>"20
0000");
2nd way:
$salary["Sonoo"]="350000";
$salary["John"]="450000";
$salary["Kartik"]="200000";

Example 1
<?php
$salary=array("Sonoo"=>"350000","John"=>"450000","Kartik"=>"200000");
echo "Sonoo salary: ".$salary["Sonoo"]." ";
echo "John salary: ".$salary["John"]." ";
echo "Kartik salary: ".$salary["Kartik"]." ";
?>
Output:
Sonoo salary: 350000
John salary: 450000
Kartik salary: 200000

Example:2
<?php
$salary["Sonoo"]="350000";
$salary["John"]="450000";
$salary["Kartik"]="200000";
echo "Sonoo salary: ".$salary["Sonoo"]." ";
echo "John salary: ".$salary["John"]." ";
echo "Kartik salary: ".$salary["Kartik"]." ";
?>
Output:
Sonoo salary: 350000
John salary: 450000
Kartik salary: 200000

PHP Multidimensional Array
 PHP multidimensional array is also known as array of arrays.
 It allows you to store tabular data in an array.
 PHP multidimensional array can be represented in the form of matrix which is represented
by row * column.
Definition:
$emp = array
(
array(1,"sonoo",400000),
array(2,"john",500000),
array(3,"rahul",300000)
);

Example of PHP multidimensional array to display following tabular data as
3 rows and 3 columns.
Id Name Salary
1 sonoo 400000
2 john 500000
3 rahul 300000

Example:
<?php
$emp = array
(
array(1,"sonoo",400000),
array(2,"john",500000),
array(3,"rahul",300000)
);
for ($row = 0; $row < 3; $row++)
{
for ($col = 0; $col < 3; $col++)
{
echo $emp[$row][$col]." ";
}
echo " ";
}
?>
Output :
1 sonoo 400000
2 john 500000
3 rahul 300000

PHP FUNCTIONS AND ARRAY.pptx

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