Generators in PHP

index.php

<?php

$start_time = microtime(true);
$startMemoryUsage = memory_get_peak_usage();

/**********************************************
WITHOUT GENERATOR
**********************************************/

$array = [];

function getData() {
    for ($i = 0; $i < 999999; $i++) {
        $array[] = $i;
    }

    return $array;
}

foreach (getData() as $data) {
    echo $data;
}


/**********************************************
WITH GENERATOR
**********************************************/


// function getData() {
//     for ($i = 0; $i < 999999; $i++) {
//         yield $i;
//     }
// }

// foreach(getData() as $data) {
//     echo $data;
// }


/**********************************************
DO NOT COMMENT OUT CODE BELOW
**********************************************/


$end_time = microtime(true);
$endMemoryUsage = memory_get_peak_usage();

echo PHP_EOL;
echo 'total execution time: ' . bcsub($end_time, $start_time, 4) . ' seconds' . PHP_EOL;
echo 'bytes used: ' . number_format($endMemoryUsage - $startMemoryUsage) . PHP_EOL;