Remove duplicate elements in Array

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Remove duplicate elements in Array

Asked 9 years, 2 months ago

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I’m getting an array by JSON, and using the array_unique to remove duplicated values, however, is displaying the following error: Notice: Array to string conversion in /var/www/html/.... on line 10 "

On line 10 is just the array_unique.

I have tried several ways, but I cannot remove these duplicate values.

Someone can help me??

Note: data sent by JSON is being received correctly.

$dados = json_decode(($_POST['dados']));
$dados_arr = array_unique($dados); //linha 10
print_r($dados_arr);

1

The error is stating that you are trying to turn a string into an array; : $dados_arr[] = $dados and then try to pass the array_unique

– RFL

2015/08/26 at 15:12
Places the json structure.

– rray

2015/08/26 at 15:20
I tried to change it like Rafaek said, but I still get the same results. Following is part of the structure: Array ( [0] => Array ( [0] => Array ( [0] => 4 [1] => 29/12/1988 [2] => S ) [1] => Array ( [0] => 4 [1] => 29/12/1988 [2] => S ) [2] => Array ( [0] => 7 [1] => [2] => N )

– Thiago Alessandro

2015/08/26 at 15:25
1

See my answer. I ran the test on the command line and it was exactly your error that occurred when I didn’t use the SORT_REGULAR!

– Wallace Maxters

2015/08/26 at 15:30
@Thiagoalessandro, just one more additional detail that I won’t add to the answer: You should use the second parameter of json_decode as true, to ensure that you will be returned a array, instead of a stdClass(object).

– Wallace Maxters

2015/08/26 at 16:05

1 answer

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by Wallace Maxters • **102,340** points · Answer 1 · 2015-08-26T15:27:05+00:00

The PHP Handbook does not detail this in the English version of the function array_unique, but in the English version, it shows that this function has a second parameter.

See the "skeleton" of this function - taken from PHP manual, array_unique, in English:

array array_unique ( array $array [, int $sort_flags = SORT_STRING ] )

The function array_unique internally uses a comparison method, which by default values are treated as strings, and that is why the error is generated.

So you have to change this form of comparison. Instead of SORT_STRING let’s use SORT_REGULAR.

Example:

$dados = json_decode(($_POST['dados']));
$dados_arr = array_unique($dados, SORT_REGULAR); //linha 10
print_r($dados_arr);

By adding the constant SORT_REGULAR in the second parameter of array_unique, it is possible to work with other values, regardless of the type of the same.

We can even use the SORT_REGULAR for make a collection of unique objects.

For more information, see the possible flags that can be used with array_unique.

SORT_REGULAR - compare items normally (does not change types)
SORT_NUMERIC - compares items numerically
SORT_STRING - compare items as strings
SORT_LOCALE_STRING - compares items as strings, based on the current location.