calling variables from inner php function to use in outer function

Question

currently I have the following code

inside my 'function.php' is

function calcTime($database_name,$currentTime){

    global $startTime;
    global $endTime;

    ...calcutions

    return $startTime;
    return $endTime;
}//end calcTime()

inside my main 'index.php' I have

include('/function.php');

$databaseName = foo;

$currentTime = 12.30;

function begin($database_name,$currentTime){

    ...some calculations

    calcTime($database_name,$currentTime); //calling the function from other file

echo $startTime;

echo $endTime;

}// end begin()

The problem I am having is that the variables that are declared inside the inner function do not pass through to the outer function. I have declared the variables globals and returned them. Not sure whats going on.

something interesting though, if I echo calcTime($database_name,$currentTime); the $startTime is returned but not $endTime.

Please help. I have functions that are used throughout other functions that I would like to use in this fashion. Thank you!!

I am not an expert in PHP global but at least I know that you do not have to return what’s global, or do not have to set global, what you return. I think (that’s where I am uncertain) that global is used when you have a variable that already exists in the outer code before you use it inside a function. But in your code $startTime is not used before the function call. Just use list($startTime, $endTime) = calcTime($database_name,$currentTime); and remove the two global commands. And of course change the two return to return array($startTime, $endTime); — aufziehvogel
– aufziehvogel, Commented Jul 14, 2012 at 19:12
You can only ever return once from a function. You may however return an array of values or an object. — knittl
– knittl, Commented Jul 14, 2012 at 19:14

knittl · Accepted Answer · 2012-07-14 19:20:58Z

2

The global keyword in PHP is used to access global variables which were declared outside of the function. It's syntactic sugar for writing $var =& $GLOBALS['var'].

There are at least two options how you could return your two variables from your function: call-by-ref or returning an array:

function calcTime($database_name,$currentTime){
    return array('start' => $startTime, 'end' =>  $endTime);
}

$times = calcTime(…, …);
echo $times['start'], ' and ', $times['end'];
// or:
list($start, $end) = calcTime(…, …);
echo $start, ' and ', $end;

Or, passing the arguments as references:

function calcTime($database_name,$currentTime, &$startTime, &$endTime){
    $startTime = …;
    $endTime = …;
}

$startTime = 0;
$endTime = 0;
calcTime(…, …, $startTime, $endTime);
echo $startTime, ' and ', $endTime;

answered Jul 14, 2012 at 19:20

knittl

269k59 gold badges339 silver badges405 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

AtkinsSJ · Accepted Answer · 2012-07-14 19:17:35Z

2

The first issue is that global in PHP is a bit counter-intuitive. I know it confused me. It doesn't make a variable inside the function accessible outside; rather, it allows you to use variables in the function which were declared outside, eg:

$foo = 'hello';
function bar() {
    global $foo;
    echo $foo;
}

What you want to do is return both the variables. However, you can only return once. As soon as PHP reaches a return statement, it ends the function, so the second one never runs.

What I'd advise doing is returning an array containing both values, eg:

return array('startTime' => $startTime, 'endTime' => $endTime);

Then, you can use extract to make them variables again:

extract( calcTime() );
echo $startTime;
echo $endTime;

answered Jul 14, 2012 at 19:17

AtkinsSJ

4822 silver badges8 bronze badges

2 Comments

brandon-estrella-dev Over a year ago

Thank you for explaining the issue with globals. I had no idea. Whats the difference between declaring a global inside the function or passing the variable through the function? for instance, in your example above, why not just function bar($foo) ? Would that be the same or is there a benefit to doing it that way?

knittl Over a year ago

Fewer globals is better. If you can pass a variable as parameter, do it.

GTSouza · Accepted Answer · 2012-07-14 19:54:03Z

2

Simply put: the calling scope isn't global scope either... So for it to work, the variables would have to be declared global there as well. Do note that (over)use of globals is considered bad practice, and a hell to debug for you fellow coders (or even you after some time has passed). Favor parameters & returns.

** remember every function is isolated on php, when you set a global or variable on one function that will be visible only on function scope

Of course, you can return only one value, but that might as well be a more complex one, like:

return array('startTime' => $startTime,'endTime' => $endTime);

edited Jul 14, 2012 at 19:54

GTSouza

3654 silver badges16 bronze badges

answered Jul 14, 2012 at 19:13

Wrikken

70.8k8 gold badges99 silver badges136 bronze badges

Collectives™ on Stack Overflow

calling variables from inner php function to use in outer function

3 Answers 3

Comments

2 Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

Comments

2 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related