Subtract an integer from an array in PHP

Question

I have a variable which is:

$sum = 42500;

I have an array that looks like this:

$targetsarray = array(
    '5000' => '',
    '5000' => '',
    '10000' => '',
    '10000' => '',
    '10000' => '',
    '10000' => '',
    '10000' => '',
    '12000' => '',
    '12000' => '',
    '15000' => '',
    '15000' => '',
    '15000' => '',
};

The key inside the $targetsarray is generated dynamically from the database so it in fact looks like this:

$targetsarray = array(
    $targets => '',
};

What I would like to achieve in the array is to subtract the $sum value by each consecutive key in the array so that the final $targetsarray looks like this:

$sum = 45000;

$targetsarray = array(
    '5000' => '40000', // subtract 5000 from 45000
    '5000' => '35000', // subtract 5000 from 40000
    '10000' => '25000', // subtract 10000 from 35000
    '10000' => '15000', // subtract 10000 from 25000
    '10000' => '5000', // subtract 10000 from 15000
    '10000' => '0', 
    '10000' => '0',
    '10000' => '0',
    '10000' => '0',
    '10000' => '0',
    '10000' => '0',
    '10000' => '0',
};

Is there anyway that I can subtract the $sum from each key in the $targetsarray? Your help will be highly appreciated from an array noobie :)

All keys of an array must be unique. You can’t have 5000 twice and 10000 ten times as the keys of an array. — Sharanya Dutta
– Sharanya Dutta, Commented Mar 3, 2014 at 1:34
Hi @SharanyaDutta, thank you for your comment. May I ask if there is a better way to do it? The keys in the array represent the monthly target for sales and the value represents the fee accumulated so there is always a possibility of duplicate keys. I've tried lots of solutions so far and none have been effective so far. Thanks! — Raja
– Raja, Commented Mar 3, 2014 at 1:43

Sharanya Dutta · Accepted Answer · 2014-03-03 02:02:59Z

2

You may simply have two arrays:

$targetsarray = array(5000, 5000, 10000, 10000, 10000, 10000, 10000, 10000, 10000, 10000, 10000, 10000);
$anotherarray = array();
$sum = 45000;
foreach($targetsarray as $val){
$anotherarray[] = $sum = ($sum >= $val) ? $sum-$val : 0;
}

edited Mar 3, 2014 at 2:02

answered Mar 3, 2014 at 1:30

Sharanya Dutta

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1 Comment

Raja Over a year ago

Wow @sharanya thank you so much I really appreciate it! I went back and forward using for & while loops. You make it look easy. Thank you again for your answer, I'll definitely be sure to learn from it :)

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