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PHP Array Exercises : Create a multidimensional unique array for any single key index

PHP Array: Exercise-38 with Solution

Write a PHP function to create a multidimensional unique array for any single key index.

Sample Solution:

PHP Code:

<?php
function unique_array($my_array, $key) { 
    $result = array(); 
    $i = 0; 
    $key_array = array(); 
    
    foreach($my_array as $val) { 
        if (!in_array($val[$key], $key_array)) { 
            $key_array[$i] = $val[$key]; 
            $result[$i] = $val; 
        } 
        $i++; 
    } 
    return $result; 
}  

$students = array( 
    0 => array("city_id"=>"1", "name"=>"Sara",  "mobile_num"=>"1111111111"), 
    1 => array("city_id"=>"2", "name"=>"Robin", "mobile_num"=>"2222222222"), 
    2 => array("city_id"=>"1", "name"=>"Sonia", "mobile_num"=>"3333333333"), 
); 

print_r(unique_array($students, "city_id"));
?>

Sample Output: 

Array                                                       
(                                                           
    [0] => Array                                            
        (                                                   
            [city_id] => 1                                  
            [name] => Sara                                  
            [mobile_num] => 1111111111                      
        )                                                   
                                                            
    [1] => Array                                            
        (                                                   
            [city_id] => 2                                  
            [name] => Robin                                 
            [mobile_num] => 2222222222                      
        )                                                   
                                                            
)

Flowchart:

Flowchart: PHP - Create a multidimensional unique array for any single key index

PHP Code Editor:

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Previous: Write a PHP script to count the total number of times a specific value appears in an array.
Next: Write a PHP program to remove duplicate values from an array which contains only strings or only integers.

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PHP: Tips of the Day

Convert a PHP object to an associative array

Just typecast it

$array = (array) $yourObject;

From Arrays:

If an object is converted to an array, the result is an array whose elements are the object's properties. The keys are the member variable names, with a few notable exceptions: integer properties are unaccessible; private variables have the class name prepended to the variable name; protected variables have a '*' prepended to the variable name.These prepended values have null bytes on either side.

Example: Simple Object

$object = new StdClass;
$object->foo = 1;
$object->bar = 2;

var_dump( (array) $object );

Output:

array(2) {
  'foo' => int(1)
  'bar' => int(2)
}

Example: Complex Object

class Foo
{
    private $foo;
    protected $bar;
    public $baz;

    public function __construct()
    {
        $this->foo = 1;
        $this->bar = 2;
        $this->baz = new StdClass;
    }
}

var_dump( (array) new Foo );

Output (with \0s edited in for clarity):

array(3) {
  '\0Foo\0foo' => int(1)
  '\0*\0bar' => int(2)
  'baz' => class stdClass#2 (0) {}
}

Output with var_export instead of var_dump:

array (
  '' . "\0" . 'Foo' . "\0" . 'foo' => 1,
  '' . "\0" . '*' . "\0" . 'bar' => 2,
  'baz' =>
  stdClass::__set_state(array(
  )),
)

Typecasting this way will not do deep casting of the object graph and you need to apply the null bytes (as explained in the manual quote) to access any non-public attributes. So this works best when casting StdClass objects or objects with only public properties. For quick and dirty (what you asked for) it's fine.

Also see this in-depth blog post:

  • Fast PHP Object to Array conversion

Ref : https://bit.ly/3fqiV2E