Convert json string to php associative array

If you see:

<?php
    header("Content-type: text/plain");
    $string = '[{title : "Comp 1 Product",columns : ["Our Vehicle","Features","Their Vehicle"], items : [["dcq","adv","asdvasdv"],["sdv","sdv","sdv"]]},{title : "qwefqw",columns : ["Section 1","Features","Section 2"],items : [["qqwec","qwe","qwegqwev"]]}]';
    print_r(json_decode($string), true);
    print_r(json_last_error());
?>

The above code returns a 4, which means JSON_ERROR_SYNTAX, which is a syntax error with JSON. When checked with JSON Lint, your JSON throws:

You need to correct it to look like:

[{
    "title": "Comp 1 Product",
    "columns": ["Our Vehicle", "Features", "Their Vehicle"],
    "items": [
        ["dcq", "adv", "asdvasdv"],
        ["sdv", "sdv", "sdv"]
    ]
}, {
    "title": "qwefqw",
    "columns": ["Section 1", "Features", "Section 2"],
    "items": [
        ["qqwec", "qwe", "qwegqwev"]
    ]
}]

What you have now is a JavaScript Object and not a valid JSON!

Apart from invalid json, print_r(json_decode($string), true); prints nothing, but returns the value. To get the result printed to the output, you need to either:

print_r(json_decode($string));

or

echo print_r(json_decode($string), true);

The former is better.