php does not let me override default parameter

Question

I can't seem to get php to accept dynamic values for parameters when I have a default specified. I've read here that the default value needs to be at the end of the function, which I've done.

$isbilling = true;

function retrieve_address($dbh, $customer_id, $isbilling=false){
echo $isbilling; //false
}

What am I doing wrong here?

score 3 · Answer 1 · answered Feb 19 '13 at 08:24

$isbilling = true;

function retrieve_address($dbh, $customer_id, $isbilling=false){
echo $isbilling; //false
}

// you have to call your function

retrieve_address('dbhval', 'CUSTID', $isbilling); // will print true
retrieve_address('dbhval', 'CUSTID'); // will print false

score 3 · Accepted Answer · answered Feb 19 '13 at 08:25

You have set the default value for $isbilling to false, and you aren't passing anything to the $isbilling parameter when you call it (I'm assuming, since you didn't actually post that part).

Try this:

$isbilling = true;

function retrieve_address($dbh, $customer_id, $isbilling=false){
    echo $isbilling; //false
}

retrieve_address($dbh, $customer_id, $isbilling);

score 0 · Answer 3 · answered Feb 19 '13 at 08:31

Well Dynamic values can be any where in the function arguments, and also can be the first ones. But the best practice is to keep them at the end, so you dont have to specify the optional parameter every time you call the function.

I also have changed the echo inside the function to return, this is also a best practice.

$isbilling = true;

function retrieve_address($dbh, $customer_id, $isbilling=false){
     return  $isbilling; //false
}


$returned = retrieve_address($dbh, $customer_id, $isbilling);

So by this you can also do the following

// will return true or false 
if(retrieve_address($dbh, $customer_id, $isbilling)){
    // if it is true, your code
}else{
    // if it is false
}

or

$returned = retrieve_address($dbh, $customer_id, $isbilling);
if(returned)){
    // if it is true, your code
}else{
    // if it is false
}

php does not let me override default parameter

3 Answers3