binary repr to int

<?php

function binaryToDecimal ($value) {
    if (gettype($value) !== 'string') {
        throw new InvalidArgumentException('Argument must be a string');
    }

    if (preg_match('/^[01]*$/', $value) !== 1) {
        throw new InvalidArgumentException('Argument must be a sequence of 1s and 0s');
    }

    $number = 0;

    for ($i = 0; $i < strlen($value); $i++) {
        $number *= 2;

        if ($value[$i] === '1') {
            $number += 1;
        }
    }

    return $number;
}

$testCases = [
    ['000', 0],
    ['001', 1],
    ['010', 2],
    ['011', 3],
    ['100', 4],
    ['101', 5],
    ['110', 6],
    ['111', 7],
];

foreach ($testCases as [$input, $expected]) {
    echo "Testing '$input', expecting $expected: ";

    $actual = binaryToDecimal($input);

    if ($actual === $expected) {
        echo "OK\n";
    } else {
        echo "Failed, got $actual\n";
    }
}