switch:case VS if:else ...?

[4rxsid]

which is faster & more efficient?
CASE or IF with 10-15 possible conditions running PHP v 4.2.2?

thanks!

[diego25]

If it's just number or string comparisons, I don't think 10-15 would make much of a difference.

Diego

[ednark]

using pears benchmark interate function...

i timed a 50 long ifelse and a 50 long case statement
matching up to 2 characters...

i timed 10,000 iterations... starting with matching the first item in the case/ifelse then the second then the third and so on...

the pear benchmark iterator can be found at http://pear.php.net

here are the results

function overhead : 0.000066 sec
case function     : 0.000083 sec
if else function  : 0.000097 sec
'case' function executed in 85.567010309278% the time of 'if else' function

here is the code

<?php

include "Benchmark/Iterate.php";

$match = array(
    'a',    'b',    'c',    'd',    'e',    'f',    'g',    'h',    'i',
    'j',    'k',    'l',    'm',    'n',    'o',    'p',    'q',    'r',
    's',    't',    'u',    'v',    'w',    'x',    'y',    'z',    'aa',
    'ab',   'ac',   'ad',   'ae',   'af',   'ag',   'ah',   'ai',   'aj',
    'ak',   'al',   'am',   'an',   'ao',   'ap',   'aq',   'ar',   'as',
    'at',   'au',   'av',   'aw',   'ax'
);

function overhead()
{
    global $match;
    static $index = 0;
    $value = $match[$index];
    $index++;
    if ( $index >= count($match) ) {
        $index = 0;
    }
}

function do_case()
{
    global $match;
    static $index = 0;
    $value = $match[$index];
    switch ( $value ) {
        case 'a': $var = $value; break;        case 'b': $var = $value; break;
        case 'c': $var = $value; break;        case 'd': $var = $value; break;
        case 'e': $var = $value; break;        case 'f': $var = $value; break;
        case 'g': $var = $value; break;        case 'h': $var = $value; break;
        case 'i': $var = $value; break;        case 'j': $var = $value; break;
        case 'k': $var = $value; break;        case 'l': $var = $value; break;
        case 'm': $var = $value; break;        case 'n': $var = $value; break;
        case 'o': $var = $value; break;        case 'p': $var = $value; break;
        case 'q': $var = $value; break;        case 'r': $var = $value; break;
        case 's': $var = $value; break;        case 't': $var = $value; break;
        case 'u': $var = $value; break;        case 'v': $var = $value; break;
        case 'w': $var = $value; break;        case 'x': $var = $value; break;
        case 'y': $var = $value; break;        case 'z': $var = $value; break;
        case 'aa': $var = $value; break;        case 'ab': $var = $value; break;
        case 'ac': $var = $value; break;        case 'ad': $var = $value; break;
        case 'ae': $var = $value; break;        case 'af': $var = $value; break;
        case 'ag': $var = $value; break;        case 'ah': $var = $value; break;
        case 'ai': $var = $value; break;        case 'aj': $var = $value; break;
        case 'ak': $var = $value; break;        case 'al': $var = $value; break;
        case 'am': $var = $value; break;        case 'an': $var = $value; break;
        case 'ao': $var = $value; break;        case 'ap': $var = $value; break;
        case 'aq': $var = $value; break;        case 'ar': $var = $value; break;
        case 'as': $var = $value; break;        case 'at': $var = $value; break;
        case 'au': $var = $value; break;        case 'av': $var = $value; break;
        case 'aw': $var = $value; break;        case 'ax': $var = $value; break;
    }
    $index++;
    if ( $index >= count($match) ) {
        $index = 0;
    }
}

function do_ifelse()
{
    global $match;
    static $index = 0;
    $value = $match[$index];

if ( $value == 'a' ) { $var = $value; } else if ( $value == 'b' ) { $var = $value; } else 
if ( $value == 'c' ) { $var = $value; } else if ( $value == 'd' ) { $var = $value; } else
if ( $value == 'e' ) { $var = $value; } else if ( $value == 'f' ) { $var = $value; } else 
if ( $value == 'g' ) { $var = $value; } else if ( $value == 'h' ) { $var = $value; } else 
if ( $value == 'i' ) { $var = $value; } else if ( $value == 'j' ) { $var = $value; } else 
if ( $value == 'k' ) { $var = $value; } else if ( $value == 'l' ) { $var = $value; } else 
if ( $value == 'm' ) { $var = $value; } else if ( $value == 'n' ) { $var = $value; } else 
if ( $value == 'o' ) { $var = $value; } else if ( $value == 'p' ) { $var = $value; } else 
if ( $value == 'q' ) { $var = $value; } else if ( $value == 'r' ) { $var = $value; } else 
if ( $value == 's' ) { $var = $value; } else if ( $value == 't' ) { $var = $value; } else 
if ( $value == 'u' ) { $var = $value; } else if ( $value == 'v' ) { $var = $value; } else 
if ( $value == 'w' ) { $var = $value; } else if ( $value == 'x' ) { $var = $value; } else 
if ( $value == 'y' ) { $var = $value; } else if ( $value == 'z' ) { $var = $value; } else 
if ( $value == 'aa' ) { $var = $value; } else if ( $value == 'ab' ) { $var = $value; } else 
if ( $value == 'ac' ) { $var = $value; } else if ( $value == 'ad' ) { $var = $value; } else 
if ( $value == 'ae' ) { $var = $value; } else if ( $value == 'af' ) { $var = $value; } else 
if ( $value == 'ag' ) { $var = $value; } else if ( $value == 'ah' ) { $var = $value; } else 
if ( $value == 'ai' ) { $var = $value; } else if ( $value == 'aj' ) { $var = $value; } else 
if ( $value == 'ak' ) { $var = $value; } else if ( $value == 'al' ) { $var = $value; } else 
if ( $value == 'am' ) { $var = $value; } else if ( $value == 'an' ) { $var = $value; } else 
if ( $value == 'ao' ) { $var = $value; } else if ( $value == 'ap' ) { $var = $value; } else 
if ( $value == 'aq' ) { $var = $value; } else if ( $value == 'ar' ) { $var = $value; } else 
if ( $value == 'as' ) { $var = $value; } else if ( $value == 'at' ) { $var = $value; } else 
if ( $value == 'au' ) { $var = $value; } else if ( $value == 'av' ) { $var = $value; } else 
if ( $value == 'aw' ) { $var = $value; } else if ( $value == 'ax' ) { $var = $value; }

$index++;
if ( $index >= count($match) ) {
    $index = 0;
}
}


$benchmark = new Benchmark_Iterate();

echo "<pre><tt>";

$benchmark->run(10000, 'overhead', $match );
$overhead = $benchmark->get();
echo "function overhead : {$overhead['mean']} sec\n";

$benchmark->run(10000, 'do_case', $match );
$case = $benchmark->get();
echo "case function     : {$case['mean']} sec\n";

$benchmark->run(10000, 'do_ifelse', $match );
$ifelse = $benchmark->get();
echo "if else function  : {$ifelse['mean']} sec\n\n";

echo "'case' function executed in ". (($case['mean']/$ifelse['mean'])*100) ."% the time of 'if else' function";

echo "</tt></pre>";

?>

[4rxsid]

thanks ednark!
that's just the info i was looking for.