Subtraction Of Arrays – Algorithm

Subtraction Of Arrays – How to get out of an array A only items that are not in array b, thus subtracting from array A all items of array B.

PHP:
We can try on our own:

<?php 
function SubtractionOfArrays($vectorA,$vectorB) 
         { 
           $countA=count($vectorA); 
           $countB=count($vectorB); 
           $numberOfElementsCaught=0; 
           for($i=0;$i<$countA;$i++) 
                { 
                 for($j=0;$j<$countB;$j++) 
                      { 
                       if($vectorA[$i]==$vectorB[$j]) 
                           $numberOfElementsCaught+=1; 
                      } 

                 if($numberOfElementsCaught==0) 
                    $new_array[]=$vectorA[$i];
                 else 
                    $numberOfElementsCaught=0;
                  
                } 
           return $new_array; 
         } 

$result = SubtractionOfArrays($array1, $array2);

print_r($result);


?>

Or we can use the simple provided array_diff:

<?php
$array1 = array("a" => "green", "red", "blue", "red");
$array2 = array("b" => "green", "yellow", "red");
$resultSimple= array_diff($array1, $array2);

print_r($resultSimple);
?>