PHP Functions

To keep the browser from executing a script when the page loads, you can put your script into a function.A function will be executed by a call to the function. You may call a function from anywhere within a page.
Create a PHP Function
A function will be executed by a call to the function.
Syntax
function functionName()
{
code to be executed;
}

PHP function guidelines:

Give the function a name that reflects what the function does
The function name can start with a letter or underscore (not a number)

Example
A simple function that writes my name when it is called:

<html>
<body>
<?php
 function writeName()
{
  echo "Arbind Mandal";
}
 echo "My name is "; writeName();
?>
</body>
</html>

<html>

<body>

<?php

function writeName()

{

echo "Arbind Mandal";

}

echo "My name is "; writeName();

</body>

</html>

Output: My name is Arbind Mandal.
PHP Functions – Adding parameters
To add more functionality to a function, we can add parameters. A parameter is just like a variable.Parameters are specified after the function name, inside the parentheses.
Example 1
The following example will write different first names, but equal last name:

<html>
<body>
<?php
function writeName($fname)
{
echo $fname . " Mandal.<br />";
}
echo "My name is "; writeName("Arbind Kumar"); echo "My sister's name is "; writeName("shreya");
echo "My brother's name is "; writeName("Manish");
?>
</body>
</html>

<html>

<body>

<?php

function writeName($fname)

{

echo $fname . " Mandal. ";

}

echo "My name is "; writeName("Arbind Kumar"); echo "My sister's name is "; writeName("shreya");

echo "My brother's name is "; writeName("Manish");

</body>

</html>

Output:
My name is Arbind Kumar Mandal
My sister’s name is Shreya Mandal
My brother’s name is Manish Mandal
Example 2
The following function has two parameters:

<html>
<body>
<?php
function writeName($fname,$punctuation)
{
echo $fname . " Mandal" . $punctuation . "<br />";
}
echo "My name is "; writeName("Arbind Kumar ",".");
echo "My sister's name is "; writeName("Shreya","!");
echo "My brother's name is "; writeName("Manish","?");
?>
</body>
</html>

<html>

<body>

<?php

function writeName($fname,$punctuation)

{

echo $fname . " Mandal" . $punctuation . " ";

}

echo "My name is "; writeName("Arbind Kumar ",".");

echo "My sister's name is "; writeName("Shreya","!");

echo "My brother's name is "; writeName("Manish","?");

</body>

</html>

Output:
My name isArbind Kumar Mandal.
My sister’s name is Shreya MAndal!
My brother’s name is Manish?

Pass by value

<?php
function addfive(&$num)
{
           $num+=5;
}
function addsix(&$num)
{
           $num+=6;
}
$orginum=10;
addfive($orginum);
echo "orginal value is :".$orginum."<br>";
addsix($orginum);
echo "orginal value is :".$orginum;
?>

<?php

function addfive(&$num)

{

$num+=5;

}

function addsix(&$num)

{

$num+=6;

}

$orginum=10;

addfive($orginum);

echo "orginal value is :".$orginum." ";

addsix($orginum);

echo "orginal value is :".$orginum;

Pass by reference

<?php
function addfive(&$num)
{
    $num+=5;
    }
function addsix(&$num)
{
   $num+=6;
    }
$orginum=10;
addfive($orginum);
echo "orginal value is :".$orginum."<br>";
addsix($orginum);
echo "orginal value is :".$orginum;
?>

<?php

function addfive(&$num)

{

$num+=5;

}

function addsix(&$num)

{

$num+=6;

}

$orginum=10;

addfive($orginum);

echo "orginal value is :".$orginum." ";

addsix($orginum);

echo "orginal value is :".$orginum;

WAP to store a information with an array displaying the value of array using function also display the no. of elements using an array

<?php
$age=array("Ram"=>20,"Hari"=>21,"Gita"=>22);
{function display($me)
              asort($me);
              foreach($me as $key=>$value)
              {
              echo " key : ".$key." value : ".$value."<br>";
                                             }
              $length=count($me);
              echo "Total no of elements is :".$length;
                       }
display($age);
?>

<?php

$age=array("Ram"=>20,"Hari"=>21,"Gita"=>22);

{function display($me)

asort($me);

foreach($me as $key=>$value)

{

echo " key : ".$key." value : ".$value." ";

}

$length=count($me);

echo "Total no of elements is :".$length;

}

display($age);

PHP Functions – Return values
To let a function return a value, use the return statement.

<?php
function subnum($num,$num2)
{
                $difference=$num-$num2;
               return $difference;
}
$result=subnum(20,10);
echo "difference of two number :".$result."<br>";
function addnum($num,$num2)
{
                $sum=$num+$num2;
                return $sum;
          
}
$result1=addnum(5,10);
echo "sum of the two number :".$result1."<br>";
?>

<?php

function subnum($num,$num2)

{

$difference=$num-$num2;

return $difference;

}

$result=subnum(20,10);

echo "difference of two number :".$result." ";

function addnum($num,$num2)

{

$sum=$num+$num2;

return $sum;

}

$result1=addnum(5,10);

echo "sum of the two number :".$result1." ";