对于using嵌套的改进

 

using System.Text;

namespace IComparable
{
    class readtxt
    {
        /// <summary>
        /// 读取Txt文件
        /// </summary>
        /// <param name="txtFilePath">Txt文件绝对路径</param>
        /// <returns>StringBuilder</returns>
        public static StringBuilder ReadTxtFile(string txtFilePath)
        {
            StringBuilder sb = new StringBuilder();

            if (System.IO.File.Exists(txtFilePath))
            {
                //using自动释放资源
                using (System.IO.FileStream FS = new System.IO.FileStream(txtFilePath, System.IO.FileMode.Open))
                using (System.IO.StreamReader SR = new System.IO.StreamReader(FS, System.Text.Encoding.Default))
                {
                    string Line = null;
                    while ((Line = SR.ReadLine()) != null)//最后一个则为空
                        sb.AppendLine(Line);
                }

            }
            else
            {
                sb = null;
            }

            return sb;
        }
    }
}

 

由

public IEnumerable<Order> GetOrders()
{
    var orders = new List<Order>();
    using (var con = new SqlConnection("some connection string"))
    {
        using (var cmd = new SqlCommand("select * from orders", con))
        {
            using (var rs = cmd.ExecuteReader())
            {
                while (rs.Read())
                {
                    // ...
                }
            }
        }
    }
    return orders;
}

出现using嵌套，影响代码的美观

对其改进：

public IEnumerable<Order> GetOrders()
{
    var orders = new List<Order>();

    using (var con = new SqlConnection("some connection string"))
    using (var cmd = new SqlCommand("select * from orders", con))
    using (var rs = cmd.ExecuteReader())
    {
        while (rs.Read())
        {
            // ...
        }
    }
    return orders;
}