No comma after last element in array?

Question

I noticed that some arrays don\'t have a comma after the last item. I have an array:

$first_name = array(
              \'name\'        => \'first_name\',         


        

Answer 1

The comma after last element may not work in every language. However it make diffs in version control systems cleaner for supported languages.

/* From */
$a = array(
    'element_w',
    'element_x',
);
/* To */
$a = array(
    'element_w',
    'element_x',
    'element_y', /* Only this line will show in version control. */
);


/* From */
$a = array(
    'element_w',
    'element_x'
);
/* To */
$a = array(
    'element_w',
    'element_x', /* These two lines               */
    'element_y'  /* will show in version control. */
);

Answer 2

Sounds like a style preference if both are syntactically correct

Answer 3

It is a style preference as mentioned elsewhere, however I would advise to condition yourself against adding that trailing comma in PHP, as it is syntactically invalid in some languages. In particular, I'm thinking of Internet Explorer's handling of those types of trailing commas in Javascript, which are notoriously difficult bugs to locate when scripts fail in IE while succeeding everywhere else. It will also break JSON's validity, and is invalid in a SQL SELECT list, among other potential problems.

Again, it's a matter of preference, but could cause you problems in other areas.

Answer 4

Both are syntactically correct in a number of languages. The last element is ignored if left blank. It is a nice little easter egg built into languages just so you don't have to keep adding in , before you start modifying an array if you manually have to add a few more values in.