PHP - Unexpected result for array_intersect

Question

$array1 = array(1=>"Band",2=>"Song", 3=>"Release",4=>"Year");
$array2 = array(1=>"Band");
print_r(array_intersect($array1,$array2));

Expected : array(1=>"Band") but i got an empty array();

You have a BOM character at the beginning of the first Band. — Barmar
– Barmar, Commented Dec 15, 2022 at 20:48

jspit · Accepted Answer · 2022-12-16 12:49:39Z

1

@Barmar has already mentioned the cause in his comment. The differences cannot be shown with print_r. var_dump shows a different length for the first element.

$array1 = array(1=>"Band",2=>"Song", 3=>"Release",4=>"Year");
$array2 = array(1=>"Band");

var_dump($array1,$array2);

Output:

array(4) {
  [1]=>
  string(7) "Band"
  [2]=>
  string(4) "Song"
  [3]=>
  string(7) "Release"
  [4]=>
  string(4) "Year"
}
array(1) {
  [1]=>
  string(4) "Band"
}

Removing the BOM before the 'Band' solves the problem. The following line only removes a BOM only if it is at the beginning of the string.

$array1[key($array1)] = preg_replace("~^\xef\xbb\xbf~u","",$array1[key($array1)]);

Try it yourself: https://3v4l.org/NYnPG

I find it commendable that the editor of 3v4l.org also shows the difference.

However, a BOM should always be removed when importing (CSV?)data .

edited Dec 16, 2022 at 12:49

answered Dec 16, 2022 at 12:40

jspit

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