PHP allows you to define C++ style default argument values. In such a case, if you don't pass any value to the function, it will use default argument value.

A simple example of using PHP default arguments in the function.

PHP Default Argument Values Function Example 1

<?php  
function myDefault($name="Suhail"){  
echo "Hello $name<br/>";  
}  
sayHello("Karan");  
sayHello();//passing no value  
sayHello("Sonia");  
?>  

Output:

Hello Karan
Hello Suhail
Hello Sonia

Note: Since PHP 5, you can use the concept of default argument value with a call by reference also.

PHP Default Argument Values Function Example 2

<?php    
function myDefault($first="Sonia",$last="Sharma"){    
echo "My Name: $first $last<br/>";    
}    
myDefault();  
myDefault("Karan");  
myDefault("Suhail","Khan");  
?>

Output:

My Name: Sonia Sharma
My Name: Karan Sharma
My Name: Suhail Khan

PHP Default Argument Values Function Example 3

<?php  
function addCal($first=10,$second=20){  
$sum=$first+$second;  
echo "Addition is: $sum<br/>";  
}  
addCal();  
addCal(90);  
addCal(50,40);  
?> 

Output:

Addition is: 30

Addition is: 100

Addition is: 90