How to upload image in php with validation || image upload in php

In this code we learn about How to upload a image or any type of file in our server using php. this is a code of codigniter 3. but doing some chages we can user this code in our core php.  and any other php framework also

public function update_profile(){

if(!($this->session->has_userdata('user_email'))){

         redirect('student/login');

    }else{

       $email= $this->session->userdata('user_email');

        if($_FILES['profile']['name'] != ''){

            $img_size   =  $_FILES['profile']['size'];

            if($img_size < 5242880){

                $filename = $_FILES['profile']['name'];

                $ext = pathinfo($filename,PATHINFO_EXTENSION);

                $valid_ext  = array("jpg","jpeg","png");

                if(in_array($ext ,$valid_ext)){

                    $new_name  =  rand().".".$ext;

                    $path      =  "assets/student/student_image/".$new_name;

                    $move =  move_uploaded_file($_FILES['profile']['tmp_name'],$path);

                    if($move){

                      $data['image']              =   $new_name;

                        $this->db->update('councellor_task', $data, array('email'=>$email));

                        $this->session->set_flashdata('img_upload','Image Susseccfully uploaded.');

                    }else{

                        $this->session->set_flashdata('img_error','Something wrong Try again.');

                    }

                }else{

                    $this->session->set_flashdata('img_error','Upload Only jpg,jpeg and png image.');

                }

            }else{

                $this->session->set_flashdata('img_error','Image less then 5mb only.');

            }

        }else{

                        $this->session->set_flashdata('img_error','Image not Selected.');

            }

                redirect(base_url().'student/account' , 'refresh');

    }

}