Replacing value of one array with value of another

Question

I have two arrays $array1 and $array2 with data as show:

$array1:

Array 
  ( 
     [0] => Array 
         ( 
            [id] => 222
            [issubtask] => true 
         ) 
     [1] => Array 
         ( 
            [id] => 444
            [issubtask] => false 
         )
  )

$array2:

Array 
  ( 
   [0] => Array 
    ( 
        [id] => 111 
        [name] => Mark 
        [isselected] => false 
        [issubtask] => false 
    ) 
   [1] => Array 
    ( 
        [id] => 222 
        [name] => Tony 
        [isselected] => false 
        [issubtask] => false 
    ) 
   [2] => Array 
    ( 
        [id] => 333 
        [name] => Jack 
        [isselected] => false 
        [issubtask] => false 
    )
   [3] => Array 
    ( 
        [id] => 444 
        [name] => Nick 
        [isselected] => false 
        [issubtask] => false 
    )   
  )

All I want to do is check for the matching 'id' in $array2 from $array1 and then replace the 'issubtask' value of $array2 for that 'id' with the value of 'issubtask' in $array1.

I tried this out but the values of $array2 are not changed:

foreach ($array1 as $val1) {
    foreach ($array2 as $val2) {
        // Checking whether IDs match
        if ($val2['id'] == $val1['id']) {
            $val2['isselected'] = "true";
            $val2['issubtask'] = $value1['issubtask'];
        }
    }
}
print_r($array2);

I am expecting the below result but I get the $array2 values as it was before.

Result $array2:

Array 
( 
[0] => Array 
    ( 
        [id] => 111 
        [name] => Mark 
        [isselected] => false 
        [issubtask] => false 
    ) 
[1] => Array 
    ( 
        [id] => 222 
        [name] => Tony 
        [isselected] => true 
        [issubtask] => true 
    ) 
[2] => Array 
    ( 
        [id] => 333 
        [name] => Jack 
        [isselected] => false 
        [issubtask] => false 
    )
[3] => Array 
    ( 
        [id] => 444 
        [name] => Nick 
        [isselected] => true 
        [issubtask] => false 
    )   
)

I am not sure whether I am doing the right way. Any help is much appreciated.
Thank you

Pierre Granger · Accepted Answer · 2014-02-05 13:33:52Z

You're changing the local value of the var, not the one really stored in your array. When you've got this :

    foreach ($array2 as $key2 => $val2) {

        // This is wrong : $val2 is a local value only in the foreach
        $val2['isselected'] = "true";

        // This is ok, you really change the value in the array
        $array2[$key2]['isselected'] = true ;
    }

Here is an answer for your problem. Be carefull to use true and not "true" also.

foreach ( $array1 as $field1 )
{
    foreach ( $array2 as $key2 => $field2 ) // Note that $field2 is just a local value in this loop
    {
        if ( $field2['id'] == $field1['id'] ) // Same ID for each field, and field1 has issubtask
        {
            // You have to change the value contained in $array2[1][222], not the value stored in $field2[issubtask] because this is a local value
            $array2[$key2]['issubtask'] = $field1['issubtask'] ; // Here you have to call the "full path" of array2[$key2]
            $array2[$key2]['isselected'] = true ;
        }
    }
}

Mario · Accepted Answer · 2014-02-05 13:20:18Z

1

Replace directly $array2 not $val2.

foreach ($array1 as $val1) {
    foreach ($array2 as $k => $v) {
        // Checking whether IDs match
        if ($v['id'] == $val1['id']) {
            $array2[$k]['isselected'] = "true";
            $array2[$k]['issubtask'] = $val1['issubtask'];
        }
    }
}
print_r($array2);

answered Feb 5, 2014 at 13:20

Mario

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