Creating an array inside another array from 2 arrays

Question

im trying to input certian items from an array into another array but as the array is being created it keeps adding items that are not suppose to go in for example

array(
       $parentcat ('id' =>'1000', 'name' => 'assets',)
                  ('id' => '2000', 'name' => 'expenses'),
       $categories('id' => '1100', 'name' =>'cash', ‘cat’ => 1000)
                  ('id' => '1200', 'name' => 'AR', ‘cat’ => 1000)
                  ('id' => '2100', 'name' => 'AP', ‘cat’ => 2000)
                  ('id' => '2200', 'name' => 'payroll', ‘cat’ => ‘2000’))

I tried looping through each array and checking if the

for($k = 0; $k < count($parentCat); $k++) {
            for ($j = 0; $j < count($categories); $j++) {
                //echo $parentCat[$k]['id'] . ' ' . $categories[$j]['cat'];
                if ($parentCat[$k]['id'] == $categories[$j]['cat']) {
                //echo $categories[$j]['cat'] . '==' . $parentCat[$k]['id'];
                $categories_dropdown[$categories[$j]['id']] = $categories[$j]['name'];
                } 
                $parent[$parentCat[$k]['name']] = $categories_dropdown;
            }                
        }

and I want this

$parentcat('assets' => array('id' =>'1100', 'name' => 'cash'),('id' =>'1200' 'name' => 'AR'),
          'expenses' => array('id' => '2100', 'name' => 'AP'),('id' => '2200' 'name' => 'payroll))


for some reason i get 

$parentcat('assets' => array('id' => '1100', 'name' => 'cash'),('id'=> '1200' 
 'name' => 'AR'),
          'expenses' => array('id' => '1100' => 'cash'),('id' =>'1200','name' => 'AR'),('id' => '2100', 'name' => 'AP'),('id' => '2200', 'name' => 'payroll))

Answer 1

I'm not sure of the output you wanted in $categories_dropdown but the following will give you your expect output of $parent. When you add to the array it should be inside the if statement

<?php 

$parentcat = [['id' =>'1000', 'name' => 'assets'], ['id' => '2000', 'name' => 'expenses']];
$categories = [ ['id' => '1100', 'name' =>'cash', 'cat' => '1000'],
            ['id' => '1200', 'name' => 'AR', 'cat' => '1000'],
            ['id' => '2100', 'name' => 'AP', 'cat' => '2000'],
              ['id' => '2200', 'name' => 'payroll', 'cat' => '2000']];


for($k = 0; $k < count($parentcat); $k++) {
    for ($j = 0; $j < count($categories); $j++) {
        if ($parentcat[$k]['id'] == $categories[$j]['cat']) {
            $categories_dropdown[$parentcat[$k]['id']] = $categories[$j]['name'];
            $parent[$parentcat[$k]['name']][] = $categories[$j];
        } 

    }                
}


echo "<pre>";
print_r($parent);
echo "</pre>";

?>

Answer 2

Simply move $parent[$parentCat[$k]['name']] = $categories_dropdown inside the if statement, otherwise you are assigning the variable no matter if the condition meets or not, but the value is only changing when the condition does meet. That's the reason why you are getting an unexpected result.