我该如何解决非法胶印类型

Question

我收到一条错误消息，指出此代码中存在非法的偏移量：

public function add_result(){


      $marks= $this->input->post('marks');
      print_r($marks);

      $subject= $this->input->post('subject');
      print_r($subject);

       $st_roll= $this->input->post('st_roll');
       print_r($st_roll);

       $marks= array($st_roll => array( $subject => $marks)); 

        foreach($marks as $key => $value){                             
            foreach($value as $sub => $value1)
            {
                echo "{$key} - {$sub} - {$value1} <br>";                              
            }                              
        }

    }

（此行中的非法偏移警告）

$marks= array($st_roll => array( $subject => $marks));

Answer 1

  public function add_result(){


    $marks= "demo10";
    $subject= "markss";
    $st_roll= "rollno15";

    $marks = array($st_roll => array( $subject => $marks)); 

    echo "<pre>";
    print_r($marks);
    echo "</pre>";

    foreach($marks as $key => $value)
    {                             
        foreach($value as $sub => $value1)
        {
            echo "{$key} - {$sub} - {$value1} <br>";                              
        }                              
    }

}

https://i.stack.imgur.com/KAgEC.png