PHP benchmark: in_array() vs. isset() vs. array_key_exists()

perf-test.php

<?php

function test($size, $iterations)
{
    // prepare arrays
    $plain = [];
    $assoc = [];
    for ($i = 0; $i < $size; $i++) {
        $value = rand();
        array_push($plain, $value);
        $assoc[$value] = true;
    }

    // run tests
    $t1 = microtime(true);
    for ($j = 0; $j < $iterations; $j++) {
        $x = in_array($j, $plain);
    }
    $t1 = microtime(true) - $t1;

    $t2 = microtime(true);
    for ($j = 0; $j < $iterations; $j++) {
        $x = isset($assoc[$j]);
    }
    $t2 = microtime(true) - $t2;

    $t3 = microtime(true);
    for ($j = 0; $j < $iterations; $j++) {
        $x = array_key_exists($j, $assoc);
    }
    $t3 = microtime(true) - $t3;

    // echo results as CSV
    printf("%s, %d, %d, %f, %f, %f\n", phpversion(), $size, $iterations, $t1, $t2, $t3);
}

echo "# PHP Version, Array Size, Iterations, in_array(), isset(), array_key_exists()\n";
for ($i = 1; $i <= 100000; $i = $i * 10) {
    test($i, 10000);
}

perf-test.sh

#!/bin/bash

for ver in 7.0 7.1 7.2 7.3; do
  echo "# running tests for version $ver"

  image=php:$ver-cli
  docker run --rm -v "$PWD":/src $image \
    bash -c "php /src/perf-test.php"
done

Results of benchmark: isset() is fastest function in all mentioned php versions.

Data as a table:

Chart with linear time axis:

Chart with logarifmic time axis (log base = 2):