Why is array_key_exists 1000x slower than isset on referenced arrays?

Question

I have found that array_key_exists is over 1000x slower than isset at check if a key is set in an array reference. Does anyone that has an understa

Answer 1

Not array_key_exists, but the removal of the reference (= NULL) causes this. I commented it out from your script and this is the result:

array_key_exists( $my_array ) 0.0059430599212646
isset( $my_array ) 0.0027170181274414
array_key_exists( $my_array_ref ) 0.0038740634918213
isset( $my_array_ref ) 0.0025200843811035

Only removed the unsetting from the array_key_exists( $my_array_ref ) part, this is the modified part for reference:

$my_array = array();
$my_array_ref = &$my_array;
$start = microtime( TRUE );
for( $i = 1; $i < 10000; $i++ ) {
    array_key_exists( $i, $my_array_ref );
    // $my_array_ref[$i] = NULL;
}
$stop = microtime( TRUE );
print "array_key_exists( \$my_array_ref ) ".($stop-$start).PHP_EOL;
unset( $my_array, $my_array_ref, $start, $stop, $i );