PHP變數引用與非引用效能比較

本文主要和大家分享PHP變數引用與非引用效能比較，希望能協助到大家。

<?php// PREVIEW：資料需要修改的就用引用，資料不需要修改的就用非引用$arrayCount = 2000;$cycleCount = 100000;// 向函數傳遞參數並做修改echo "向函數傳遞參數並做修改", PHP_EOL;function ByVal($p){return $p[intval(count($p) / 2)] += 1;}  function ByRef(&$p){return $p[intval(count($p) / 2)] += 1;}$p = array_fill(0, $arrayCount, 1);$start = microtime(true);$startMem = Memory_get_usage();for($i = 0; $i < $cycleCount; $i += 1){    $a = ByVal($p);}$end = microtime(true);$endMem = Memory_get_usage();echo 'ByValFun: ', $end - $start, 's' , PHP_EOL, 'Mem: ', $endMem - $startMem , PHP_EOL;$start = microtime(true);$startMem = Memory_get_usage();for($i = 0; $i < $cycleCount; $i += 1){    $a = ByRef($p);}$end = microtime(true);$endMem = Memory_get_usage();echo 'ByRefFun: ', $end - $start, 's' , PHP_EOL, 'Mem: ', $endMem - $startMem , PHP_EOL , PHP_EOL;// END: 速度相近，記憶體引用勝出// 向函數傳遞參數不做修改echo "向函數傳遞參數不做修改", PHP_EOL;function ByVal2($p){return $p[intval(count($p) / 2)];}  function ByRef2(&$p){return $p[intval(count($p) / 2)];}$p = array_fill(0, $arrayCount, 1);$start = microtime(true);$startMem = Memory_get_usage();for($i = 0; $i < $cycleCount; $i += 1){    $a = ByVal2($p);}$end = microtime(true);$endMem = Memory_get_usage();echo 'ByValFun: ', $end - $start, 's' , PHP_EOL, 'Mem: ', $endMem - $startMem , PHP_EOL;$start = microtime(true);$startMem = Memory_get_usage();for($i = 0; $i < $cycleCount; $i += 1){    $a = ByRef2($p);}$end = microtime(true);$endMem = Memory_get_usage();echo 'ByRefFun: ', $end - $start, 's' , PHP_EOL, 'Mem: ', $endMem - $startMem , PHP_EOL , PHP_EOL;// END: 傳值效能大幅勝出，記憶體相近// 變數賦值做修改echo "變數賦值做修改", PHP_EOL;$start = microtime(true);$startMem = Memory_get_usage();for($i = 0; $i < $cycleCount; $i += 1){    $p = array_fill(0, $arrayCount, 1);    $a = $p;    $a[2] += 1;}$end = microtime(true);$endMem = Memory_get_usage();echo 'ByVal: ', $end - $start, 's' , PHP_EOL, 'Mem: ', $endMem - $startMem , PHP_EOL;$start = microtime(true);$startMem = Memory_get_usage();for($i = 0; $i < $cycleCount; $i += 1){    $p = array_fill(0, $arrayCount, 1);    $a = &$p;    $a[2] += 1;}$end = microtime(true);$endMem = Memory_get_usage();echo 'ByRef: ', $end - $start, 's' , PHP_EOL, 'Mem: ', $endMem - $startMem , PHP_EOL , PHP_EOL;// END 速度相近，引用略勝；記憶體引用大幅勝出// 變數賦值不做修改echo "變數賦值不做修改", PHP_EOL;$start = microtime(true);$startMem = Memory_get_usage();for($i = 0; $i < $cycleCount; $i += 1){    $p = array_fill(0, $arrayCount, 1);    $a = $p;    $b = $a[2];}$end = microtime(true);$endMem = Memory_get_usage();echo 'ByVal: ', $end - $start, 's' , PHP_EOL, 'Mem: ', $endMem - $startMem , PHP_EOL;$start = microtime(true);$startMem = Memory_get_usage();for($i = 0; $i < $cycleCount; $i += 1){    $p = array_fill(0, $arrayCount, 1);    $a = &$p;    $b = $a[2];}$end = microtime(true);$endMem = Memory_get_usage();echo 'ByRef: ', $end - $start, 's' , PHP_EOL, 'Mem: ', $endMem - $startMem , PHP_EOL , PHP_EOL;// END 速度相近，記憶體相近// 數組內迴圈賦值修改資料echo "數組內迴圈賦值修改資料", PHP_EOL;$start = microtime(true);$startMem = Memory_get_usage();for($i = 0; $i < $cycleCount; $i += 1){    $p = array_fill(0, $arrayCount, 1);    foreach($p as $key => $val){        $p[$key] += 1;    }}$end = microtime(true);$endMem = Memory_get_usage();echo 'ByKey: ', $end - $start, 's' , PHP_EOL, 'Mem: ', $endMem - $startMem , PHP_EOL;$start = microtime(true);$startMem = Memory_get_usage();for($i = 0; $i < $cycleCount; $i += 1){    $p = array_fill(0, $arrayCount, 1);    foreach($p as &$val){        $val += 1;    }}$end = microtime(true);$endMem = Memory_get_usage();echo 'ByRef: ', $end - $start, 's' , PHP_EOL, 'Mem: ', $endMem - $startMem , PHP_EOL , PHP_EOL;// END: 引用勝出// 數組內迴圈賦值不修改資料echo "數組內迴圈賦值不修改資料", PHP_EOL;$start = microtime(true);$startMem = Memory_get_usage();for($i = 0; $i < $cycleCount; $i += 1){    $p = array_fill(0, $arrayCount, 1);    foreach($p as $key => $val){        $b = $val;    }}$end = microtime(true);$endMem = Memory_get_usage();echo 'ByKey: ', $end - $start, 's' , PHP_EOL, 'Mem: ', $endMem - $startMem , PHP_EOL;$start = microtime(true);$startMem = Memory_get_usage();for($i = 0; $i < $cycleCount; $i += 1){    $p = array_fill(0, $arrayCount, 1);    foreach($p as &$val){        $b = $val;    }}$end = microtime(true);$endMem = Memory_get_usage();echo 'ByRef: ', $end - $start, 's' , PHP_EOL, 'Mem: ', $endMem - $startMem , PHP_EOL;// END: 傳值勝出// 總結：資料需要修改的就用引用，資料不需要修改的就用非引用