PHP 函数效率优化实战指南

$arr = [1, 2, 3, 4, 5];
$total = 0;

// 优化前
foreach ($arr as $item) {
    $total += $item;
}

// 优化后
foreach ($arr as $item) {
    $total += $item;
}
// 在循环外计算总和
$total;

// 优化前
function add_numbers($a, $b) {
    return $a + $b;
}

// 优化后
function add_numbers(int $a, int $b) {
    return $a + $b;
}

// 优化前
function get_current_time() {
    return date('Y-m-d H:i:s');
}

// 优化后
function get_current_time() {
    static $time;
    if ($time === null) {
        $time = date('Y-m-d H:i:s');
    }
    return $time;
}

// 优化前
$numbers = [1, 2, 3, 4, 5];
$squared = [];
foreach ($numbers as $number) {
    $squared[] = $number * $number;
}

// 优化后
$numbers = [1, 2, 3, 4, 5];
$squared = array_map(function($number) {
    return $number * $number;
}, $numbers);

// Xdebug 性能分析

function my_function() {
    // ...
}

my_function();
xdebug_start_trace();
my_function();
xdebug_stop_trace();