PHP: Fastest way to handle undefined array key

Question

in a very tight loop I need to access tenthousands of values in an array containing millions of elements. The key can be undefinied: In that case it shall be legal to return

Answer 1

I did some bench marking with the following code:

set_time_limit(100);

$count = 2500000;
$search_index_end = $count * 1.5;
$search_index_start = $count * .5;

$array = array();
for ($i = 0; $i < $count; $i++)
    $array[md5($i)] = $i;

$start = microtime(true);
for ($i = $search_index_start; $i < $search_index_end; $i++) {
    $key = md5($i);
    $test = isset($array[$key]) ? $array[$key] : null;
}
$end = microtime(true);
echo ($end - $start) . " seconds
";

$start = microtime(true);
for ($i = $search_index_start; $i < $search_index_end; $i++) {
    $key = md5($i);
    $test = array_key_exists($key, $array) ? $array[$key] : null;
}
$end = microtime(true);
echo ($end - $start) . " seconds
";


$start = microtime(true);
for ($i = $search_index_start; $i < $search_index_end; $i++) {
    $key = md5($i);
    $test = @$array[$key];
}
$end = microtime(true);
echo ($end - $start) . " seconds
";

$error_reporting = error_reporting();
error_reporting(0);
$start = microtime(true);
for ($i = $search_index_start; $i < $search_index_end; $i++) {
    $key = md5($i);
    $test = $array[$key];
}
$end = microtime(true);
echo ($end - $start) . " seconds
";
error_reporting($error_reporting);

$start = microtime(true);
for ($i = $search_index_start; $i < $search_index_end; $i++) {
    $key = md5($i);
    $tmp = &$array[$key];
    $test = isset($tmp) ? $tmp : null;
}
$end = microtime(true);
echo ($end - $start) . " seconds
";

and I found that the fastest running test was the one that uses isset($array[$key]) ? $array[$key] : null followed closely by the solution that just disables error reporting.