PlayerController 3D

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class PlayerController : MonoBehaviour {
    public float speed = 25.0F;
     public float jumpSpeed = 8.0F;
     public float gravity = 20.0F;
     private Vector3 moveDirection = Vector3.zero;
     private float turner;
     private float looker;
     public float sensitivity = 5;

     // Use this for initialization
     void Start () {

     }

     // Update is called once per frame
     void Update () {
         CharacterController controller = GetComponent<CharacterController>();
         // is the controller on the ground?
         if (controller.isGrounded) {
             //Feed moveDirection with input.
             moveDirection = new Vector3(Input.GetAxis("Horizontal"), 0, Input.GetAxis("Vertical"));
             moveDirection = transform.TransformDirection(moveDirection);
             //Multiply it by speed.
             moveDirection *= speed;
             //Jumping
             if (Input.GetButton("Jump"))
                 moveDirection.y = jumpSpeed;

         }
         turner = Input.GetAxis ("Mouse X")* sensitivity;
         looker = -Input.GetAxis ("Mouse Y")* sensitivity;
         if(turner != 0){
             //Code for action on mouse moving right
             transform.eulerAngles += new Vector3 (0,turner,0);
         }
         if(looker != 0){
             //Code for action on mouse moving right
             transform.eulerAngles += new Vector3 (looker,0,0);
         }
         //Applying gravity to the controller
         moveDirection.y -= gravity * Time.deltaTime;
         //Making the character move
         controller.Move(moveDirection * Time.deltaTime);
     }
}