PHP determines whether an array is a numeric array

PHP determines that the array is a numerical array

Specific idea: Get all the keys of the array: "array_keys()"

Traverse all keys to determine whether each key starts from 0 and increases by one in order.

The specific method is as follows: (Recommended learning: PHP programming from entry to proficiency)

function _checkAssocArray($arr)
    {
        $index = 0;
        foreach (array_keys($arr) as $key) {
            if ($index++ != $key) return false;
        }
        return true;
    }

The logic is very simple, associative array The keys will not all increase in the order: 0,1,2,3..., if it does, then there is no difference from the numerical array, just treat it the same way.

function is_assoc($arr) {
return array_keys($arr) !== range(0, count($arr) - 1);
}

Test

$arr = array(1, 2, 3, 4, 5, 6, 7);
print is_assoc($arr); // 输出false
$arr = array("foo" => "bar", "bar" => "foo");
print is_assoc($arr); // 输出true
$arr = array("foo" => "bar", 3, 4, 5);
print is_assoc($arr); // 输出true

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