How to properly use array_key_exists

Question

$array = json_decode('[{"1234567":1368356071},{"7654321":1368356071}, etc, etc]');
$array2 = array(array(1234567 => time()), array(7654321 => time()));
   foreach($array2 as $key){
      if(!array_key_exists(key($key),$array))
           array_push($array, $key);
   }

Why are $keys that are in $array still getting pushed through to $array?

Pretty much I'm trying to prevent duplicate keys from getting pushed into $array..

error in code foreach($array2 as $key){ replace foreach($array2 as $key => $val){ — Nick Maroulis, May 12 '13 at 11:42

score 2 · Accepted Answer · answered May 12 '13 at 11:42

2

Try This

You had three problems

1) You were decoding array into stdObject, it should be set true to return it to array

2) You need to loop array as foreach($array2 as $key => $val)

3) Pass as $array[0] in array_key_exists function

  $array = json_decode('[{"1234567":1368356071}]', true);

$array2 = array(1234567 => time(), 7654321 => time());
//echo count($array);
foreach($array2 as $key => $val){


    if(!array_key_exists($key,$array[0]))
        array_push($array, $key);
}
echo count($array);

answered May 12 '13 at 11:42

chandresh_cool

11,753
3
30
45

foreach($array2 as $key => $val){ seems to be pushing the index not the key – GameDevGuru May 12 '13 at 12:06
Pretty much I'm trying to prevent duplicate keys from getting pushed into $array.. – GameDevGuru May 12 '13 at 12:57

Yogesh Suthar · Answer 2 · 2013-05-12T12:45:07.940

1

Because $array is 2 dimensional array and $array2 is 1D array, use below code

<?php

$array = json_decode('[{"1234567":1368356071}]',true);
print_r($array);
$array2 = array(array(1234567 => time()), array(7654321 => time()));
echo count($array);
foreach($array2 as $key){    

  if(!array_key_exists($key[0],$array[0]))
       array_push($array, $key);
}
echo count($array);

?>

Output

1
2

Codepad

edited May 12 '13 at 12:45

answered May 12 '13 at 11:41

Yogesh Suthar

30,424
18
72
100

@Yogesh Suthar how is array2 1D, isn't it the same as array but with 2 keys? – GameDevGuru May 12 '13 at 11:57
@GameDevGuru Yes array2 is with 2 keys but a 1 Dimensional array. – Yogesh Suthar May 12 '13 at 12:16
@YogeshSuthar Oh okay i understand. My code had a mistake. Array2 is also 2D – GameDevGuru May 12 '13 at 12:32
@YogeshSuthar This works but not very well. What if i had multiple values in array1? [{"1234567":1368356071}, {"7654321":1368356071}] $array[0] searches only the first one.. – GameDevGuru May 12 '13 at 12:52
@YogeshSuthar Pretty much I'm trying to prevent duplicate keys from getting pushed into $array.. – GameDevGuru May 12 '13 at 12:56

mpyw · Answer 3 · 2013-05-12T16:03:55.633

The keyword isset works faster than the function array_key_exists.
You should use isset if you don't have to tell Undefined from NULL.

array_key_exists:

array_key_exists($key,$array);

isset:

isset($array[$key]);

Tested on Ideone:
http://ideone.com/m1Do1d

To prevent duplicate keys from getting pushed into $array, it works with this code:

<?php

$array = json_decode('[{"1234567":1368356071}]', true);
$array2 = array(array(1234567 => time()), array(7654321 => time()));

var_dump(
    '$array (before)', $array,
    '$array2', $array2
);

foreach ($array2 as $item2) {    
    foreach ($array as $item) {
        if (isset($item[key($item2)])) {
            continue 2;
        }
    }
    $array[] = $item2;
}

var_dump(
    '$array (after)', $array
);

Result:

string(15) "$array (before)"
array(1) {
  [0]=>
  array(1) {
    [1234567]=>
    int(1368356071)
  }
}
string(7) "$array2"
array(2) {
  [0]=>
  array(1) {
    [1234567]=>
    int(1368650316)
  }
  [1]=>
  array(1) {
    [7654321]=>
    int(1368650316)
  }
}
string(14) "$array (after)"
array(2) {
  [0]=>
  array(1) {
    [1234567]=>
    int(1368356071)
  }
  [1]=>
  array(1) {
    [7654321]=>
    int(1368650316)
  }
}

isn't that only checking if that index is set? I need to search an array to see if a key already exists before pushing — GameDevGuru, May 12 '13 at 12:33
Pretty much I'm trying to prevent duplicate keys from getting pushed into $array.. — GameDevGuru, May 12 '13 at 12:56
Needless to say, you should just replace array_key_exists to isset, in other answers' codes... — mpyw, May 12 '13 at 15:32
And you don't need to use array_push. array_push is required only if you push several items at once. — mpyw, May 12 '13 at 16:09

How to properly use array_key_exists

3 Answers3