<?php
$testCases = array(
    '[1,2,3]',
    '{"one":1,"two":2,"three":3}',
    '"1"',
    '1'
);

foreach ($testCases as $testCase) {
    echo "INPUT:", PHP_EOL;
    echo $testCase, PHP_EOL;
    echo "OUTPUT:", PHP_EOL;
    var_dump(json_decode($testCase));
    echo PHP_EOL;
}