Why is this array key being set to zero?

Question

function getMonths() {
        $data[] = array('key' => 01, 'name' => 'January');
        $data[] = array('key' => 02, 'name' => 'February');
        $data[] = array('key' => 03, 'name' => 'March');
        $data[] = array('key' => 04, 'name' => 'April');
        $data[] = array('key' => 05, 'name' => 'May');
        $data[] = array('key' => 06, 'name' => 'June');
        $data[] = array('key' => 07, 'name' => 'July');
        $data[] = array('key' => 08, 'name' => 'August');
        $data[] = array('key' => 09, 'name' => 'September');
        $data[] = array('key' => 10, 'name' => 'October');
        $data[] = array('key' => 11, 'name' => 'November');
        $data[] = array('key' => 12, 'name' => 'December');
        error_log("data:");
        error_log(print_r($data,1));

        return $data;
    }

For some reason I can't fathom, August and September's keys are 0 when I print_r the $data array, instead of 08 and 09.

[03-Jan-2014 15:28:26] data:
[03-Jan-2014 15:28:26] Array
(
    [0] => Array
        (
            [key] => 1
            [name] => January
        )

    [1] => Array
        (
            [key] => 2
            [name] => February
        )

    [2] => Array
        (
            [key] => 3
            [name] => March
        )

    [3] => Array
        (
            [key] => 4
            [name] => April
        )

    [4] => Array
        (
            [key] => 5
            [name] => May
        )

    [5] => Array
        (
            [key] => 6
            [name] => June
        )

    [6] => Array
        (
            [key] => 7
            [name] => July
        )

    [7] => Array
        (
            [key] => 0
            [name] => August
        )

    [8] => Array
        (
            [key] => 0
            [name] => September
        )

    [9] => Array
        (
            [key] => 10
            [name] => October
        )

    [10] => Array
        (
            [key] => 11
            [name] => November
        )

    [11] => Array
        (
            [key] => 12
            [name] => December
        )

)

What am I missing here?

can you use the key as strings?

schingeldi
– schingeldi

2014-01-03 21:34:21 +00:00
Commented Jan 3, 2014 at 21:34 — schingeldi
– schingeldi, Commented Jan 3, 2014 at 21:34

Lightness Races in Orbit · Accepted Answer · 2014-01-04 01:45:57Z

2

Literals beginning 0 are octal literals. Where decimal is a numeric system with 10 digits, octal is a numeric system with only 8 digits. 08, 09 etc are therefore numbers that do not exist. An analogous example is the non-existent hexadecimal literal 0xG.

Just write 8 and 9 like a normal person ;)

Incidentally, that seems like a rather strange way to use an array. Why not this:

function getMonths()
{
    return Array(
        1  => 'January',
        2  => 'February',
        // ...
        12 => 'December'
    );
}

http://www.php.net/manual/en/language.types.integer.php

If you are interfacing with some external system that requires a specific representation of those keys, where that specific representation is a string with a leading zero, then use strings:

function getMonths()
{
    return Array(
        '01' => 'January',
        '02' => 'February',
        // ...
        '12' => 'December'
    );
}

edited Jan 4, 2014 at 1:45

answered Jan 3, 2014 at 21:35

Lightness Races in Orbit

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5 Comments

EmmyS Over a year ago

I'm not sure what you mean by, "like a normal person." Do you mean without the leading 0? Not possible; the point of sale system that this data gets posted to requires leading zeroes for single-digit months.

Lightness Races in Orbit Over a year ago

@EmmyS: Huh? No it doesn't! Your keys are integers so the string representation doesn't even exist. If you need strings then use them, but the moment you sit on integer literals you promise to abide by the rules of the language's integer-to-string conversion rules.

Let me see Over a year ago

"like a normal person" was epic :)

EmmyS Over a year ago

@LightnessRacesinOrbit - wow, that was rude. I asked an honest question; I don't see the need for snark. I've been working with PHP for a number of years and never run into this issue. And to respond: yes, it does. The new third-party POS does require two-digit months to be sent in. So do you think, in your infinite wisdom, you could please just explain what you mean by "like a normal person"? Without being an ass about it?

Lightness Races in Orbit Over a year ago

@EmmyS: There was no snark. No, your third-party POS does not require two-digit integer literals because this makes no sense. They are a part of your source code and do not even exist at runtime. Did you read the second part of my answer where I address this concern? After using PHP for a number of years I would expect you to know the difference between a string and an integer.

Community · Accepted Answer · 2023-11-17 20:38:18Z

2

You need to put them in quotes. '08', '09', etc. Otherwise PHP thinks you are using Octal numbers.

Octal: http://en.wikipedia.org/wiki/Octal

PHP Ints: https://www.php.net/manual/en/language.types.integer.php

edited Nov 17, 2023 at 20:38

CommunityBot

11 silver badge

answered Jan 3, 2014 at 21:33

Jessica

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1 Comment

zerkms Over a year ago

Explanation of why it happens might be useful

Iłya Bursov · Accepted Answer · 2014-01-03 21:34:47Z

1

Numbers starting with zero (0) are octal in PHP, so 08 and 09 are invalid numbers, check out more: http://www.php.net/manual/en/language.types.integer.php

to fix: remove leading zeros or enclose in single quotes

answered Jan 3, 2014 at 21:34

Iłya Bursov

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Comments

Abhik Chakraborty · Accepted Answer · 2014-01-03 21:44:18Z

0

Here is an alternative to your function

function getMonths() {
    for ($x=0; $x < 12; $x++) {

        $time = strtotime('+' . $x . ' months', strtotime(date('Y-M' . '-01')));
        $key = date('m', $time);
        $name = date('F', $time);
        $months[$key] = $name;
    }
    return $months ;
}

output is as

Array ( [01] => January [02] => February [03] => March [04] => April [05] => May [06] => June [07] => July [08] => August [09] => September [10] => October [11] => November [12] => December )

answered Jan 3, 2014 at 21:44

Abhik Chakraborty

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