errors while uploading images in php

Notice: Undefined index:
picture in C:\xampp\htdocs\page1.php on line 33

Warning: pathinfo() expects parameter 2 to be long, string given in
C:\xampp\htdocs\page1.php on line 35
Sorry, only JPG, JPEG, PNG & GIF
files are allowed.Sorry, your file was not uploaded. User Logged
in

////session_start();
//if
            (!isset($_SESSION['login_user'])) {
 //header ("Location:
            page2.php");/
//}

//?> 

            
 
 


 

            




            

 session_start();
 $servername =
            "localhost";
 $username = "root";
 $passwor = "";
 $dbname
            = "form";
 $name = $_SESSION['login_user'];
 echo $name;
            


 $conn = new PDO("mysql:host=$servername;dbname=form",
            $username, $passwor);

 $stmt = $conn->prepare("SELECT id,
            username, password FROM users where username='$name'");
 $result =
            $stmt->setFetchMode(PDO::FETCH_ASSOC); 
 echo "Connected successfully";
            
 $target_dir= "htdocs" ."basketball/";
 $target_file =
            '$target_dir' .basename($_FILES['picture']['name']); //heres an error 

            $uploadOk = 1;

            $imageFileType=pathinfo('$targetfile','PATHINFO_EXTENSION');//heres an
            error


 if(isset($_POST["submit"])) 

            {
 $check = getimagesize($_FILES['picture']['tmp_name']);
 if($check
            !== false) {
 echo "File is an image - " . $check["mime"] . ".";

            $uploadOk = 1;
 } 
 else {
 echo "File is not an
            image.";

 $uploadOk = 0;
 }
}

            if($imageFileType != "jpg" && $imageFileType != "png" && $imageFileType
            != "jpeg" && $imageFileType != "gif" ) 
 {
 echo "Sorry,
            only JPG, JPEG, PNG & GIF files are allowed.";
 $uploadOk = 0;

            } 
 if ($uploadOk == 0) 
 {

 echo "Sorry, your
            file was not uploaded.";
 } 
 else 
 {
 if
            (move_uploaded_file($_FILES['picture']['tmp_name'], $target_file)) {
 echo
            "The file ". basename( $_FILES["picture"]["name"]). " has been uploaded.";
 }
            else {
 echo "Sorry, there was an error uploading your file.";

            }
}


            ?>








User
            Logged in


            enctype="multipart/form-data">
            value="picture">





if(isset($_POST['logout'])){
//$_SESSION['user_login']
            =
            '';

//die;
session_destroy();
header("Location:
            login.php");}
?>