Winform開發遇到的問題之TabPage頁籤禁用

1.代碼塊：

//預設加載
        private void Form1_Load(object sender, EventArgs e)
        {
            tabPage();
        }

        //頁籤預設值
        private void tabPage()
        {
            for (int i = ; i < tab.TabCount; i++)
            {
                this.tab.TabPages[i].Tag = true;
            }
        }

        //頁籤判斷
        private void tabControl1_Selecting(object sender, TabControlCancelEventArgs e)
        {
            if (!string.IsNullOrEmpty(e.TabPage.Tag.ToString()) && !Convert.ToBoolean(e.TabPage.Tag))
            {
                e.Cancel = true;
            }
        }
        //修改按鈕
        private void btn_Click(object sender, EventArgs e)
        {
            int tabindex = tab.SelectedIndex;
            for (int i = ; i < tab.TabCount; i++)
            {
                if (tabindex != i)
                {
                    this.tab.TabPages[i].Tag = false;
                }
            }

        }
        //取消或儲存按鈕
        private void button1_Click(object sender, EventArgs e)
        {
            tabPage();
        }
           

2.效果圖：