我不认为您可以在没有任何解决方法的情况下即时访问数组值，并且您已经将insert放在了foreach之外。
你最好多花点时间在这些上面。
1.代码索引
1.使用正确的IDE。不像记事本。
1.调试所有和每一行的错误。
这样做。
由于您没有使用批量插入，因此可以逐个插入。

$cal1 = $this->input->post('exam_group_student_ca1_' . $exam_group_student_value);
$cal2 = $this->input->post('exam_group_student_ca1_' . $exam_group_student_value);
$cal3 = $this->input->post('exam_group_student_ca1_' . $exam_group_student_value);
$cal4 = $this->input->post('exam_group_student_ca1_' . $exam_group_student_value);
$exam = $this->input->post('exam_group_student_ca1_' . $exam_group_student_value);

$total = $cal1 + $cal2 + $cal3 + $cal4 + $exam;

$array = array(
    'exam_group_class_batch_exam_subject_id' => $this->input->post('exam_group_class_batch_exam_subject_id'),
    'exam_group_class_batch_exam_student_id' => $exam_group_student_value,
    'attendence' => $attendance,
    'get_ca1' => $cal1,
    'get_ca2' => $cal2,
    'get_ca3' => $cal3,
    'get_ca4' => $cal4,
    'get_exam' => $exam,
    'note' => $this->input->post('exam_group_student_note_' . $exam_group_student_value)
);

if ($total > 0) {
    $this->examgroupstudent_model->add_result($array);
}

最终代码是

public function entrymarks()
{
    $this->form_validation->set_error_delimiters('', '');
    $this->form_validation->set_rules('exam_group_class_batch_exam_subject_id', 'Subject', 'required|trim|xss_clean');

    if ($this->form_validation->run() == false) {
        $data = array(
            'exam_group_class_batch_exam_subject_id' => form_error('exam_group_class_batch_exam_subject_id'),
        );
        $array = array('status' => 0, 'error' => $data);
        echo json_encode($array);
    } else {

        $exam_group_student_id = $this->input->post('exam_group_student_id');

        $insert_array = array();
        $update_array = array();
        if (!empty($exam_group_student_id)) {
            foreach ($exam_group_student_id as $exam_group_student_key => $exam_group_student_value) {
                $attendance_post = $this->input->post('exam_group_student_attendance_' . $exam_group_student_value);
                if (isset($attendance_post)) {
                    $attendance = $this->input->post('exam_group_student_attendance_' . $exam_group_student_value);
                } else {
                    $attendance = "present";
                }

                $cal1 = $this->input->post('exam_group_student_ca1_' . $exam_group_student_value);
                $cal2 = $this->input->post('exam_group_student_ca1_' . $exam_group_student_value);
                $cal3 = $this->input->post('exam_group_student_ca1_' . $exam_group_student_value);
                $cal4 = $this->input->post('exam_group_student_ca1_' . $exam_group_student_value);
                $exam = $this->input->post('exam_group_student_ca1_' . $exam_group_student_value);

                $total = $cal1 + $cal2 + $cal3 + $cal4 + $exam;

                $array = array(
                    'exam_group_class_batch_exam_subject_id' => $this->input->post('exam_group_class_batch_exam_subject_id'),
                    'exam_group_class_batch_exam_student_id' => $exam_group_student_value,
                    'attendence' => $attendance,
                    'get_ca1' => $cal1,
                    'get_ca2' => $cal2,
                    'get_ca3' => $cal3,
                    'get_ca4' => $cal4,
                    'get_exam' => $exam,
                    'note' => $this->input->post('exam_group_student_note_' . $exam_group_student_value)
                );

                if ($total > 0) {
                    $this->examgroupstudent_model->add_result($array);
                }
            }
        }
    }

    $array = array('status' => '1', 'error' => '', 'message' => $this->lang->line('success_message'));
    echo json_encode($array);
}