Notice and warnings-free way to retrieve the first element of array

Question

Let's suppose we have 2 functions. First returns an array with 0..N elements and the second need to return only the first element or NULL if there are no any.

Assuming we have such a code:

/**
 * return stdClass[]
 */
function foo()
{
    return ...;
}

/**
 * return stdClass|null
 */
function bar()
{
    $arr = foo();

    if ($arr) {
        return $arr[0];
    }
}

As you can see the implementation of bar() is boring.

If I used .NET then I would use arr.FirstOrDefault() method and it would suit the task perfectly.

What would be the most elegant way of doing that in php?

PS: the answers that generate any kind of warnings or notices are not accepted. As well as the ones that use @ to suppress errors

`array_shift($arr)` doesn't generate notices (and returns null). -1 for boring question — nice ass, Oct 22 '13 at 01:45
@onetrickpony It also has side effects, so for the purpose of peeking at a value it's considered bad form. — Ja͢ck, Oct 22 '13 at 02:03

score 5 · Accepted Answer · edited May 23 '17 at 10:27

5

You could use current() for that, assuming foo() doesn't change the array pointer (using next() for instance), coupled with a ternary operator:

return current(foo()) ?: null;

This will obviously have odd results if you have scalars in your array that evaluate to false, but will work fine if all elements are objects.

Alternatively, to guard against modifications done by foo() you could use reset() as well:

return reset((foo())) ?: null;

Warning

Note the extra parentheses in the above code, they're not superfluous and is based on a peculiarity in the language; this behaviour may change in the future, so you shouldn't rely on it. It would be safer to introduce a temporary variable.

edited May 23 '17 at 10:27

Community

1
1

answered Oct 22 '13 at 01:48

Ja͢ck

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You can find out more from [this answer](http://stackoverflow.com/a/6732876/1338292). – Ja͢ck Oct 22 '13 at 02:10
just a note: that would return null if foo() returns false – Oct 22 '13 at 02:15
@Wes "Let's suppose we have 2 functions. First returns an array with 0..N elements". – Ja͢ck Oct 22 '13 at 02:17
Yep, I *intentionally* declared `foo` to return `stdClass[]` – zerkms Oct 22 '13 at 02:18
@Jack: you probably need to mention that the latter solution (with weird parentheses) is not an expected behaviour and may break one day – zerkms Oct 22 '13 at 02:20
@zerkms Fair enough, added :) – Ja͢ck Oct 22 '13 at 02:27

sectus · Answer 2 · 2013-10-23T01:20:18.330

1

$return = ($arr = foo()) ? reset($arr) : null;

Why you cannont use current

function foo()
    {
    $array = array(1,2,3);
    next($array);
    return $array;
    }

echo current(foo()); // 2

edited Oct 23 '13 at 01:20

answered Oct 22 '13 at 01:45

sectus

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"Why you cannont use current" --- because it wouldn't return `NULL` – zerkms Oct 22 '13 at 02:13

Notice and warnings-free way to retrieve the first element of array

2 Answers2