Considering array like:
$arr = array(
'key' => 'foo'
'key2' => 'bar',
0 => 'num_foo',
1 => 'num_bar'
);
How to extract values under 0 & 1? (Besides using for loop). Maybe any standard function do the job?
3 Answers
If you’re using a PHP version >= 5.6, you can use array_filter, with the flag that tells it to pass the key to the callback function.
$arr = array(
'key' => 'foo',
'key2' => 'bar',
0 => 'num_foo',
1 => 'num_bar'
);
$new_array = array_filter($arr, function($key) {
return is_numeric($key);
}, ARRAY_FILTER_USE_KEY);
var_dump($new_array);
Edit: As Robbie pointed out, using is_numeric is the better choice here. (Previously my example used is_int.)
Edit 2: Perhaps is_int is actually the better choice here. is_numeric would return true for values such as +0123.45e6, or hexadecimal/binary number notations as well – not sure if that’s desired.
is_int would normally return false for a value such as '1'. It works here, because we are dealing with arrays – and PHP automatically converts array keys to integer, if they are an “integer string.”
you can use array_filter() to return the numeric keys
// $Your_array is your original array with numeric and string keys
// array_filter() returns an array of the numeric keys
$numerickeys = array_filter(array_keys($Your_array), function($k) {return is_int($k);});
// this is a simple case where the filter function is a plain
// built-in function requiring one argument, it can be passed as a string:
// Really, this is all that's needed:
$numerickeys = array_filter(array_keys($Your_array), 'is_int');
Comments
If you use is_int() inside a foreach loop it's easy enough. Try this:
foreach ($arr as $key => $value) {
if (is_int($key)) {
echo "Found integer key with value: $value\n";
}
}
If you desperately want to avoid using a loop, try this:
array_walk($arr, function($val, $key) {
if (is_int($key)) {
echo "Found integer key with value: $val\n";
}
});
That does, of course, use a loop internally anyway.
6 Comments
scrowler
Question says "besides using a loop"
TwoStraws
His comment was "I just prefer inliner", which is a bizarre thing to say. Nevertheless I'll update my answer.
DevMed
But internally we have loop written in C (am I right?) and I have big arrays.
TwoStraws
That's a remarkable leap in logic, and definitely premature optimisation. Using array_walk() will call a PHP function once for every item in the array. Is that more efficient than looping directly in PHP? I would be surprised if so. Unless your arrays are genuinely epic in scale, give it a try with a loop first and only optimise when you need to.
DevMed
Good point. Second reason for using inliner is readability improvement. I thought that there is a better way for this than array_filter etc, because in this case code readability is even worse IMO.
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is_int,is_numeric...$out = array_filter($arr, function ($key) { return is_numeric($key); }, ARRAY_FILTER_USE_KEY);