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POWhy is array_key_exists 1000x slower than isset on referenced arrays?
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copied!<p>I have found that <code>array_key_exists</code> is over 1000x slower than <code>isset</code> at check if a key is set in an array reference. Does anyone that has an understanding of how PHP is implemented explain why this is true?</p> <p>EDIT: I've added another case that seems to point to it being overhead required in calling functions with a reference.</p> <p><strong>Benchmark Example</strong></p> <pre><code>function isset_( $key, array $array ) { return isset( $array[$key] ); } $my_array = array(); $start = microtime( TRUE ); for( $i = 1; $i < 10000; $i++ ) { array_key_exists( $i, $my_array ); $my_array[$i] = 0; } $stop = microtime( TRUE ); print "array_key_exists( \$my_array ) ".($stop-$start).PHP_EOL; unset( $my_array, $my_array_ref, $start, $stop, $i ); $my_array = array(); $start = microtime( TRUE ); for( $i = 1; $i < 10000; $i++ ) { isset( $my_array[$i] ); $my_array[$i] = 0; } $stop = microtime( TRUE ); print "isset( \$my_array ) ".($stop-$start).PHP_EOL; unset( $my_array, $my_array_ref, $start, $stop, $i ); $my_array = array(); $start = microtime( TRUE ); for( $i = 1; $i < 10000; $i++ ) { isset_( $i, $my_array ); $my_array[$i] = 0; } $stop = microtime( TRUE ); print "isset_( \$my_array ) ".($stop-$start).PHP_EOL; unset( $my_array, $my_array_ref, $start, $stop, $i ); $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] = 0; } $stop = microtime( TRUE ); print "array_key_exists( \$my_array_ref ) ".($stop-$start).PHP_EOL; unset( $my_array, $my_array_ref, $start, $stop, $i ); $my_array = array(); $my_array_ref = &$my_array; $start = microtime( TRUE ); for( $i = 1; $i < 10000; $i++ ) { isset( $my_array_ref[$i] ); $my_array_ref[$i] = 0; } $stop = microtime( TRUE ); print "isset( \$my_array_ref ) ".($stop-$start).PHP_EOL; unset( $my_array, $my_array_ref, $start, $stop, $i ); $my_array = array(); $my_array_ref = &$my_array; $start = microtime( TRUE ); for( $i = 1; $i < 10000; $i++ ) { isset_( $i, $my_array_ref ); $my_array_ref[$i] = 0; } $stop = microtime( TRUE ); print "isset_( \$my_array_ref ) ".($stop-$start).PHP_EOL; unset( $my_array, $my_array_ref, $start, $stop, $i ); </code></pre> <p><strong>Output</strong></p> <pre><code>array_key_exists( $my_array ) 0.0056459903717 isset( $my_array ) 0.00234198570251 isset_( $my_array ) 0.00539588928223 array_key_exists( $my_array_ref ) 3.64232587814 // <~ what on earth? isset( $my_array_ref ) 0.00222992897034 isset_( $my_array_ref ) 4.12856411934 // <~ what on earth? </code></pre> <p>I'm on PHP 5.3.6.</p> <p><a href="http://codepad.org/UNhgiSSY">Codepad example</a>.</p>

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