Implement dynamic array sorting based on user input

Question

So I am wanting to sort an array depending on what the user selects, I have managed to get it all working (With a little help from you guys) and now I am trying to clean up the code. This is what I've got

//Global Sorting Functions (For Rows to Columns)
//Function to sort up or down
function cmpdwn($a, $b) {
    return strcasecmp($a["Name"], $b["Name"]);
}

function cmpup($a, $b, $c) {
    return strcasecmp($b[$c], $a[$c]);
}

//Name Ordering Function ---------------------------------
function nameorder($data) {
    //If Up sorts Assending if Down Decending
    if ($_POST['Sortby'] == "NameDown") {
        uasort($data, "cmpdwn");
    } else {
        uasort($data, "cmpup");
    }

    $nameorder = array();
    $count = 0;
    while (list($key, $value) = each($data)) {
        $nameorder[$count] = $key;
        $count++;
    }
    return $nameorder;
}

This creates an array for an order to print the data in name order, I will be repeating this for email too and others. What I wanted to do is re-use the "cmp" function by putting more than $a and $b into (i.e. $c = "Name" then I can put in "Email" or what ever // cmpup as example). But to from the little I know is that this function is declaring an argument for uasort and I don't send variables into it. Is there a way to do so or is it a case of re writing the function repeatedly.

for the purpose of enhancing your code, I guess codereview.stackexchange.com is better place to ask :) — ariefbayu
– ariefbayu, Commented Jun 18, 2014 at 11:00

Unlink · Accepted Answer · 2014-06-18 11:15:30Z

2

Try to make object

class MyComparator {

    private $key;

    function __construct($key) {
        $this->key = $key;
    }

    function compare($a, $b) {
        return strcasecmp($b[$this->key], $a[$this->key]);
    }

    public function setKey($key) {
        $this->key = $key;
    }
}

And use it

$compararor = new MyComparator("Name");

usort($data, array($compararor, "compare"));

OR in php >= 5.3.0. you can use __invoke() method

class MyComparator {

    private $key;

    function __construct($key) {
        $this->key = $key;
    }

    function __invoke($a, $b) {
        return strcasecmp($b[$this->key], $a[$this->key]);
    }

    public function setKey($key) {
        $this->key = $key;
    }
}

And simple call it with

$compararor = new MyComparator("Name");

usort($data, $compararor);

edited Jun 18, 2014 at 11:15

answered Jun 18, 2014 at 11:06

Unlink

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Comments

num8er · Accepted Answer · 2014-06-18 11:00:40Z

0

try this:

// $a is N-th element, $b is next element and $arguments is array of arguments to use in compare logic
usort($array, function($a, $b) use ($arguments) {
     if($a>$b) return 1;
     if($a<$b) return -1;
     foreach($arguments as $argument) {
        if($a==$argument) {
           // return -1;0;1 as you wish
        }
     }
     return 0;
});

answered Jun 18, 2014 at 11:00

num8er

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5 Comments

user3596598 Over a year ago

Sorry, so use $arguements to input the part of the array i want to compare i.e. "Name" or "Email" then just use $arguements where i've used "Name"?

num8er Over a year ago

Your problem was to pass third or more parameters to sorting function. so in my example I use closure to pass it. it could be anything for example use($someArg, $anotherArg) taken from here: php.net//manual/en/functions.anonymous.php

mickmackusa Over a year ago

I am not convinced that this pseudo-code is correctly designed.

num8er Over a year ago

@mickmackusa thank You for Your comment, me also after 10 years since 2014, seems like I was giving idea to put sorting logic inside comparator function, I just don't touch it as part of history. Please propose best solution as an answer.

mickmackusa Over a year ago

I am afraid I find the question too Unclear to answer. There is no minimal reproducible example.

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