关于拼接字符串无效的问题

Question

StringBuilder s = new StringBuilder();

this.ddlGoodsClassName.SelectedValue = "3";

s=s .Append("0");
s=s.Append(this.ddlGoodsClassName.SelectedValue.ToString().Trim()); 
s=s.Append("000001");
goods.GoodsId =Convert.ToString(s);

执行后显示的依然是3,而我要的效果是03000001，如何解决？

Answer 1

StringBuilder s = new StringBuilder();//对的this.ddlGoodsClassName.SelectedValue = "3";s=s .Append("0");//错的，而直接：s .Append("0")s=s.Append(this.ddlGoodsClassName.SelectedValue.ToString().Trim()); //和上面一样！不用等于！s=s.Append("000001");//同上goods.GoodsId =Convert.ToString(s);//goods.GoodsId = s.ToString()