PHP what is the best way to handle a variable that may not be set?

Question

I have a foreach loop, that will loop through an array, but the array may not exist depending on the logic of this particular application.

My question relates to I guess best practices, for example, is it ok to do this:

if (isset($array))
{

    foreach($array as $something)
    {
        //do something
    }
}

It seems messy to me, but in this instance if I dont do it, it errors on the foreach. should I pass an empty array?? I haven't posted specific code because its a general question about handling variables that may or may not be set.

Answer 1

Try:

 if(!empty($array))
 {
     foreach($array as $row)
     {
         // do something
     }
 }

Answer 2

That's not messy at all. In fact, it's best practice. If I had to point out anything messy it would be the use of Allman brace style, but that's personal preference. (I'm a 1TBS kind of guy) ;)

I'll usually do this in all of my class methods:

public function do_stuff ($param = NULL) {
    if (!empty($param)) {
        // do stuff
    }
}

A word on empty(). There are cases where isset is preferable, but empty works if the variable is not set, OR if it contains an "empty" value like an empty string or the number 0.

Answer 3

If you pass an empty array to foreach then it is fine but if you pass a array variable that is not initialized then it will produce error.

It will work when array is empty or even not initialized.

if( !empty($array) && is_array($array) ) {
   foreach(...)
}

Answer 4

Just to note: here is the 'safest' way.

if (isset($array) && is_array($array)) {
    foreach ($array as $item) {
        // ...
    }
}

Answer 5

I would say it is good practice to have a 'boolean' other value that is set as 0 (PHP's false) to start, and any time some function adds to this array, add +1 to the boolean, so you'll have a definite way to know if you should mess with the array or not?

That's the approach I would take in an object oriented language, in PHP it could be messier, but still I find it best to have a deliberate variable keeping track, rather than try to analyze the array itself. Ideally if this variable is always an array, set the first value as 0, and use it as the flag:

 <?PHP
 //somewhere in initialization
 $myArray[0] = 0;
 ...
 //somewhere inside an if statement that fills up the array
 $myArray[0]++;
 $myArray[1] = someValue;

 //somewhere later in the game:
 if($myArray[0] > 0){          //check if this array should be processed or not
      foreach($myArray as $row){     //start up the for loop
           if(! $skippedFirstRow){   //$skippedFirstRow will be false the first try
                $skippedFirstRow++;  //now $skippedFirstRow will be true
                continue;            //this will skip to the next iteration of the loop
           }
           //process remaining rows - nothing will happen here for that first placeholder row
      }
 }
 ?>