Setting Default Values - PHP

When creating a function that takes arguments, you can set default values for it:

function function_name($argument2, $argument = 6){

statements

}

Why would you want to set default values in a function? Well, if you are for example writing a program that involves calculating tax, which does not change often but does change sometimes, a function like this would be appropriate. It allows the assumption of a value, but still permits you to change the value when needed.

The default value is overwritten when you specify a value, otherwise the value will stay the same. For example, let's create a new function that will take your age, first name and last name:

function mydetails($firstname, $lastname, $age=23){

echo "My name is " .$firstname. " " .$lastname. " and I am
".$age." years old.";

}

To call this function, type: mydetails(34,'John','Doe')

And the result will be...

My name is John Doe and I am 34 years old

As you can see, the default value of 23 has been overwritten to 34.

If, for example, you call this function without the $age argument, the function will assume that $firstname is the first argument. In other words, it will replace $age with $firstname and $firstname with $lastname. In that case, when you call this function, the results will be:

My name is Doe and I am John years old.

Just make sure that you write the default values after the other standard values (the arguments without defaults):

function mydetails($firstname, $lastname, $age=23){

echo "My name is " .$firstname. " " .$lastname. " and I am
".$age." years old.";

}

This is because PHP assigns the values directly to the arguments as they are received from the call line.