PHP - Remove duplicates with foreach?

Question

I have a array of page numbers:

foreach($elements as $el) {
$pageno = $el->getAttribute("pageno");

echo  $pageno ;
}

Sadly it contains duplicates. I tried the follow code but it won't return a thing:

foreach(array_unique($elements) as $el) {
$pageno = $el->getAttribute("pageno");

echo  $pageno ;
}

How to remove the duplicate page numbers? Thanks in advance :)

It works as I'd expect, 3v4l.org/iPoZk. Perhaps $elements is not an array? getAttribute sounds like domdocument object maybe? — chris85
– chris85, Commented Oct 2, 2017 at 12:40
@GrumpyCrouton he actually use array_unique in the second foreach — Frankich
– Frankich, Commented Oct 2, 2017 at 13:11
@MacBooc That makes even less sense to me unless it's a multi-dimensional array. In which case, just use it twice. — GrumpyCrouton
– GrumpyCrouton, Commented Oct 2, 2017 at 13:12
@GrumpyCrouton i think it's even an array of object with different values while he use getAttribute inside his loop, so array_unique can't work here imo — Frankich
– Frankich, Commented Oct 2, 2017 at 13:14

raidenace · Accepted Answer · 2017-10-02 13:43:55Z

14

Since I do not have your data structure, I am providing a generic solution. This can be optimized if we know the structure of $elements but the below should work for you.

$pageNos = array();
foreach($elements as $el) {
   $pageno = $el->getAttribute("pageno");
   if(!in_array($pageno, $pageNos))
   {
       echo $pageno ;
       array_push($pageNos,$pageno);
   }
}

Basically we are just using an additional array to store the printed values. Each time we see a new value, we print it and add it to the array.

edited Oct 2, 2017 at 13:43

answered Oct 2, 2017 at 12:39

raidenace

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2 Comments

Jack Over a year ago

Thank you! This worked very well. Got a syntax error though. Fixed by adding a ; after 'array_push($pageNos,$pageno)'. :) Is there also a way to sort this array? It echo's: 7 6 8 1 2 3 4 5 now. I would love to have it like: 1 2 3 4 5 6 7 8.

GrumpyCrouton Over a year ago

@Jack You could probably just do PHP's sort() after the foreach and then loop through the elements afterwards again to display the page numbers.

stuiterveer · Accepted Answer · 2017-10-02 13:26:05Z

2

Apart from the answers already provided, you can also use array_unique().

A very simple example:

$pageno = array_unique($pageno);

answered Oct 2, 2017 at 13:26

stuiterveer

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Comments

Tom · Accepted Answer · 2017-10-02 12:48:33Z

1

You can create a temporary list of page numbers. Duplicate instances will then be removed from the list of $elements:

// Create a temporary list of page numbers
$temp_pageno = array();
foreach($elements as $key => $el) {
    $pageno = $el->getAttribute("pageno");
    if (in_array($pageno, $temp_pageno)) {
        // Remove duplicate instance from the list
        unset($elements[$key]);
    }
    else {
        // Ad  to temporary list
        $temp_pageno[] = $pageno;
    }

    echo  $pageno ;
}

answered Oct 2, 2017 at 12:48

Tom

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