php: array_unique missing a duplicate

Question

I have been struggling with a minor issue with the array_unique for a couple of days now.

Somehow the output always leaves the last duplicate in the array.

I am getting the text from a text box in an html form

$IDs = trim($_POST['IDs']);
$IDs = explode("\n", $IDs);
$IDs = array_filter($IDs, 'trim');
$ID = array_unique($IDs,0);
print_r($ID);

sample input:

012345 0123456 01234567 012345 0123456 01234567 012345 0123456 01234567 sample output:

Array ( [0] => 012345 [1] => 0123456 [2] => 01234567 [3] => 01234567 )

sample input:

012345 0123456 01234567 012345 0123456 01234567 012345 0123456 sample output:

Array ( [0] => 012345 [1] => 0123456 [2] => 01234567 [3] => 0123456 )

not sure why the last duplicate keeps getting missed.

Am sure I am missing something but cannot seem to figure it out.

Added the foreach loop hoping to fix it but even with that I keep getting the same result.

Why are you doing this: isset($k[$v]) || ($k[$v]=1) && $ID[] = $v;? — segFault
– segFault, Commented Sep 24, 2016 at 19:05
even without the loop, I was missing the duplicate. Thought if I just loop through it again, the problem with will resolved but it didnt. even if I dont run the loop the issue remains. — rm65453
– rm65453, Commented Sep 24, 2016 at 19:06
isset($k[$v]) || ($k[$v]=1).... this will always evaluate to true, since you are setting $k[$v] = 1. Maybe $k[$v] == 1 — Martavis Griffin
– Martavis Griffin, Commented Sep 24, 2016 at 19:06
This is just a guess. But looking at your sample input, both the final values in each array seem to have a trailing space, which if true, will make them unique. The first values in both the inputs seem to have a space preceding them as well. — wandering-geek
– wandering-geek, Commented Sep 24, 2016 at 19:06

segFault · Accepted Answer · 2016-09-24 19:11:03Z

2

You should use array_map instead of array_filter.

Like:

$IDs = trim($_POST['IDs']);
$IDs = explode("\n", $IDs);
$IDs = array_map('trim', $IDs);
$ID = array_unique($IDs,0);
print_r($ID);

answered Sep 24, 2016 at 19:11

segFault

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2 Comments

rm65453 Over a year ago

This did the trick. Thanks to @kkaosninja as well for pointing out the space thing. Google did bring up the issues with array_filter vs array_map.

mertyildiran Over a year ago

Without knowing the value of $_POST['IDs'] how did you answered this question?

Death-is-the-real-truth · Accepted Answer · 2016-11-17 09:43:07Z

-1

I have corrected your data format and foreach() is unnecessary:-

<?php

$IDs = "012345\n0123456\n01234567\n012345\n0123456\n01234567\n012345\n0123456\n01234567";

$IDs = explode("\n", $IDs);
$IDs = array_unique($IDs,0);

print_r($IDs);

?>

and the output will be:

Array
(
    [0] => 012345
    [1] => 0123456
    [2] => 01234567
)

P.S. I realized that also array_filter was unnecessary.

edited Nov 17, 2016 at 9:43

Death-is-the-real-truth

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answered Sep 24, 2016 at 19:09

mertyildiran

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10 Comments

mertyildiran Over a year ago

@Anant I didn't change array structure. Formatting of the input in the question was faulty/wrong.

rm65453 Over a year ago

not sure where you made the changes. could you highlight them?

segFault Over a year ago

@mertyildiran IRL you don't always have control over inputs used.

mertyildiran Over a year ago

@sebastianForsberg Then give me the input in correct formatting please.

rm65453 Over a year ago

The input is coming from a text box. might be the correct answer but does not work for me due to my restrictions on the input.

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