范型List 转化为数组的demo

private string _connText = "Data Source=.;Initial Catalog=OnlineBooks;Integrated Security=True";

public ResponseInfo GetBooksInfo()

{
ResponseInfo responseInfo = new ResponseInfo();
List<BooksInfo> list = new List<BooksInfo>();
try
{
using (SqlConnection conn = new SqlConnection(_connText))
{
conn.Open();
SqlCommand cmd = new SqlCommand("select * from Books", conn);
using (SqlDataReader rdr = cmd.ExecuteReader())
{
while (rdr.Read())
{
BooksInfo info = new BooksInfo();
info.BookName = rdr["BookName"].ToString();
info.BookNo = rdr["BookNo"].ToString();
info.BookImgName = rdr["BookImgName"].ToString();
info.Price = Convert.ToDecimal(rdr["Price"]);
list.Add(info);
}
}
}
responseInfo.IsSuccess = true;

//自己写的转化方法
BooksInfo[] booksInfoArr = new BooksInfo[list.Count];
for (int i = 0; i < list.Count; i++)
{
booksInfoArr[i] = new BooksInfo();//先声明再给它赋值
booksInfoArr[i].BookNo = list[i].BookNo;
booksInfoArr[i].BookName = list[i].BookName;
booksInfoArr[i].BookImgName = list[i].BookImgName;
booksInfoArr[i].Price = list[i].Price;
}
responseInfo.Data = booksInfoArr;

//微软自带的转化方法

//BooksInfo[] booksArr = list.ToArray();
//responseInfo.Data = booksArr;
}
catch (Exception exc)
{
// log
responseInfo.IsSuccess = false;
responseInfo.Msg = exc.Message;
}

return responseInfo;

}

此段代码理解起来其实很简单，但是当时我理解错了，怎么也弄不对，最后请教一哥们，他让我在循环的时候在声明对象，问题才得到解决。

希望这个能帮助你完成你所希望的结果。