arraylist contains key

Author: doganoo

src/Datastructure/Lists/ArrayLists/ArrayList.php

@@ -223,6 +223,20 @@ public function remove($key): bool {
         return false;
     }
 
+    /**
+     * whether the array contains $key or not.
+     *
+     * @param  int $key
+     * @return bool
+     */
+    public function containsKey(int $key): bool {
+        $array = $this->array;
+        $array = \array_filter($array, function ($value, $key) {
+            return $value !== null;
+        }, \ARRAY_FILTER_USE_BOTH);
+        return array_key_exists($key, $array);
+    }
+
     /**
      * removes all elements in the array that are null or equal to empty string
      *

tests/Lists/ArrayLists/ArrayListTest.php

@@ -1,7 +1,4 @@
 <?php
-
-use doganoo\PHPAlgorithms\Datastructure\Lists\ArrayLists\ArrayList;
-
 /**
  * MIT License
  *
@@ -25,6 +22,9 @@
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  * SOFTWARE.
  */
+
+use doganoo\PHPAlgorithms\Datastructure\Lists\ArrayLists\ArrayList;
+
 class ArrayListTest extends \PHPUnit\Framework\TestCase {
     public function testAdd() {
         $arrayList = new ArrayList();
@@ -60,6 +60,23 @@ public function testAdd() {
         $this->assertTrue($arrayList->length() === 8);
     }
 
+    public function testContainsKey() {
+        $arrayList = new ArrayList();
+        $arrayList->add("five");
+        $arrayList->add("six");
+        $arrayList->add("seven");
+        $arrayList->add("eight");
+
+        $this->assertTrue(true === $arrayList->containsKey(0));
+        $this->assertTrue(true === $arrayList->containsKey(1));
+        $this->assertTrue(true === $arrayList->containsKey(2));
+        $this->assertTrue(true === $arrayList->containsKey(3));
+        $this->assertTrue(false === $arrayList->containsKey(4));
+        $this->assertTrue(false === $arrayList->containsKey(50));
+        $this->assertTrue(false === $arrayList->containsKey(150));
+
+    }
+
     public function testClear() {
         $arrayList = new ArrayList();
         $arrayList->add("one");