PHP Performance: if/elseif vs case/switch vs nested if

PHP Performance: if,elseif vs case,switch vs nested if.php

<?php
$iter = 500000;


$start = microtime(true);
$n = 0;
for ($c=0; $c<7*$iter; $c++) {
    $i = $c % 16;
    
    if     ($i===0) $n += 0;
    elseif ($i===1) $n -= 1;
    elseif ($i===2) $n -= 2;
    elseif ($i===3) $n += 3;
    elseif ($i===4) $n += 4;
    elseif ($i===5) $n -= 5;
    elseif ($i===6) $n -= 6;
    elseif ($i===7) $n += 7;
    elseif ($i===8) $n += 0;
    elseif ($i===9) $n -= 1;
    elseif ($i===10) $n -= 2;
    elseif ($i===11) $n += 3;
    elseif ($i===12) $n += 4;
    elseif ($i===13) $n -= 5;
    elseif ($i===14) $n -= 6;
    elseif ($i===15) $n += 7;
}
echo 'RESULT: ';
echo microtime(true) - $start. " (FLAT IF)\n";
// RESULT: 0.45587396621704 (FLAT IF)


$start = microtime(true);
$n = 0;
for ($c=0; $c<7*$iter; $c++) {
    $i = $c % 16;
    
    switch ($i) {
        case 0:
            $n += 0;
            break;
        case 1:
            $n -= 1;
            break;
        case 2:
            $n -= 2;
            break;
        case 3:
            $n += 3;
            break;
        case 4:
            $n += 4;
            break;
        case 5:
            $n -= 5;
            break;
        case 6:
            $n -= 6;
            break;
        case 7:
            $n += 7;
            break;
        case 8:
            $n += 0;
            break;
        case 9:
            $n -= 1;
            break;
        case 10:
            $n -= 2;
            break;
        case 11:
            $n += 3;
            break;
        case 12:
            $n += 4;
            break;
        case 13:
            $n -= 5;
            break;
        case 14:
            $n -= 6;
            break;
        case 15:
            $n += 7;
            break;
    }
}
echo 'RESULT: ';
echo  microtime(true) - $start. " (SWITCH CASE)\n";
// RESULT: 0.33157801628113 (SWITCH CASE)




$start = microtime(true);
$n = 0;
for ($c=0; $c<7*$iter; $c++) {
    $i = $c % 16;
    if ($i<8) {   
        if ($i < 4) {
            if ($i < 2) {
                if ($i===0) $n += 0;
                else $n -= 1;
            } else {
                if ($i===2) $n -= 2;
                else $n += 3;
            }
        } else {
            if ($i < 6) {
                if ($i===4) $n += 4;
                else $n -= 5;
            } else {
                if ($i===6) $n -= 6;
                else $n += 7;
            }
        }
    } else {  
        if ($i < 12) {
            if ($i < 10) {
                if ($i===8) $n += 0;
                else $n -= 1;
            } else {
                if ($i===10) $n -= 2;
                else $n += 3;
            }
        } else {
            if ($i < 14) {
                if ($i===12) $n += 4;
                else $n -= 5;
            } else {
                if ($i===14) $n -= 6;
                else $n += 7;
            }
        }
    }
}
echo 'RESULT: ';
echo microtime(true) - $start . " (NESTED IF)\n";
// RESULT: 0.25623297691345 (NESTED IF)