winform彈窗添加後傳值

主窗體：

AddCodeForm ACForm = new AddCodeForm();
if (ACForm.ShowDialog() == DialogResult.OK)
{
    string code = "";
    ACForm.GetCode(ref code);
}

彈窗窗體：

public void GetCode(ref string code)
{
    code = textBox1.Text;
}
private void button1_Click(object sender, EventArgs e)
{
    this.DialogResult = DialogResult.OK;
}