4

I've read some tutorials on here but none of them return what I need. I have two arrays.

$arrayA = array(1960,1961,1963,1962,1954,1953,1957,1956,1955);
$arrayB = array(1949,1960,1961,1963,1962,1954,1953,1957,1956,1955);

However, when I run array_diff, it returns an empty array.

$diff = array_diff($arrayA, $arrayB);

But I'd like it to return 1949. What's the error in my code?

edit: since switching the variables won't work, i did var_dump for the 3 arrays (A, B, and diff) and here's the pastebin http://pastebin.com/tn1dvCs3

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  • 3
    1949 is in both of the arrays in pastebin. What is the expected output? Commented Apr 18, 2013 at 4:17

6 Answers 6

Reset to default
9

array_diff works by finding the elements in the first array that aren't in the second, per the documentation. Try inverting your call:

$diff = array_diff($arrayB, $arrayA);

To see this in action, lets look at a more manageable but equivalent example:

$arrayA = array(1960);
$arrayB = array(1949,1960);

$diff = array_diff($arrayB, $arrayA);
var_dump($diff);

This yields:

[mylogin@aserver ~]$ vim test.php
[mylogin@aserver ~]$ php test.php
array(1) {
  [0]=>
  int(1949)
}

Please note that this uses a minimal demonstrative example of the functionality you're attempting to get. By discarding unnecessary data in your actual implementation you can more quickly zero in on the problem you're having.

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2 Comments

still returning an empty array for me. i updated the main post with more info
@user2036066 I have tested this code, as shown above, and it works. Your pastebin shows two arrays with no diff: they contain the same elements, so naturally this won't yield anything.
2

Returns an array containing all the entries from array1 that are not present in any of the other arrays.

Therefore:

$diff = array_diff($arrayB, $arrayA);

will give you the result you're after.

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1 Comment

Still returning an empty array for me
1

Swap variables in array_diff call:

<?php
$arrayA = array(1960,1961,1963,1962,1954,1953,1957,1956,1955);
$arrayB = array(1949,1960,1961,1963,1962,1954,1953,1957,1956,1955);

$diff = array_diff($arrayB, $arrayA);

var_dump($diff);
?>

Shows:

array(1) { [0]=> int(1949) }
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1

Give,

$diff = array_diff($arrayB, $arrayA);

To have result of 1949, ie the element $arrayB has and $arrayA has not.

ie

$arrayA = array(1960,1961,1963,1962,1954,1953,1957,1956,1955);
$arrayB = array(1949,1960,1961,1963,1962,1954,1953,1957,1956,1955);

$diff = array_diff($arrayB, $arrayA);

print_r($diff );

Test Here

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0

you can read document here http://php.net/manual/pt_BR/function.array-diff.php

$diff = array_diff($arrayB, $arrayA);
print_r($diff);
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0 
$a = '5,6,'; 
$b = '6,6,'; 
$a_array = explode(',',$a); 
$b_array = explode(',',$b);
$result = array_diff($b_array,$a_array); 
var_dump($result);

However, when I run array_diff, it returns an empty array.

$result = array_diff($b_array,$a_array);

But I'd like it to return 6. What's the error in my code?

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