A benchmark of several methods for checking if PHP array is associative

isAssocArrayBench.php

<?php
$iterations = $argv[1] ?: 10000;
/**
 * Arrays to check
 */
$tests = array(
	array(array(
		'foo' => 'bar',
	)),
	array(array(
		'bar',
		'foo' => 'bar',
		'baz',
	)),
	array(null),
	array(true),
	array(false),
	array(0),
	array(1),
	array(0.0),
	array(1.0),
	array('string'),
	array(array(0, 1, 2)),
	array(new stdClass),
	array_fill(0, 1000, uniqid()),                // big numeric array

	array_fill_keys(range(2, 1000, 3), uniqid()),  // big misaligned numeric array (=associative)

	array_fill_keys(                            // big associative array
		str_split(
			str_repeat(uniqid('', true), 100),
			3
		),
		true
	)
);

/**
 * Common methods to check associative array
 */
$methods = array(
	'if (array_key_first($array)!==0) return true; return array_values($array) !== $array;' =>
		function ($array)
		{
			if (array_key_first($array) !== 0)
			{
				return true;
			}
			return array_values($array) !== $array;
		},

	'return array_values($array) !== $array;' =>
		function ($array)
		{
			return array_values($array) !== $array;
		},

	'return range(0,count($array)) !== array_keys($array);' =>
		function ($array)
		{
			return range(0, count($array)) !== array_keys($array);
		},

	'array_keys($array); return $array !== array_keys($array);' =>
		function ($array)
		{
			$array = array_keys($array);
			return ($array !== array_keys($array));
		},

	'return count(array_filter(array_keys($array), "is_string")) > 0;' =>
		function ($array)
		{
			return count(array_filter(array_keys($array), "is_string")) > 0;
		},
	'foreach...$i++' =>
		function ($array)
		{
			$i = 0;
			foreach ($array as $k => $v)
			{
				if ($i !== $k)
				{
					return true;
				}
				$i++;
			}
			return false;
		},
//	'for...key...next' =>
//		function ($array)
//		{
//			$l = count($array);
//			for ($i = 0; $i < $l; $i++)
//			{
//				if (key($array) !== $i)
//				{
//					return true;
//				}
//				next($array);
//			}
//			return false;
//		},
);

/**
 * Perform benchmark on each method
 */
echo "Testing $iterations iterations on PHP version ".phpversion()."\n";

foreach ($methods as $name => $func)
{
	echo "$name\n";
	$time = microtime(true);

	for ($x = 0; $x < $iterations; $x++)
	{
		foreach ($tests as $array)
		{
			$func($array);
		}
	}

	/**
	 * Show results
	 */
	$totalTime = (microtime(true) - $time);
	$avgTime = $totalTime / ($iterations * count($tests));

	echo "  Total time: " . number_format($totalTime, 5, '.', ' ') . " s\n";
	echo "  Average   : " . number_format($avgTime * 1000, 5, '.', ' ') . " ms / test \n";
	echo "\n";
}