如何判断二维数组在C#中的应用价值？

Question

我用asp.net编程，定义两个维数组，如何判断数组值为空？

数组：

            #region inital Festival
            string[,] holidays = new string[13, 32];
            holidays[1, 1] = "元旦";
            holidays[2, 14] = "情人节";
            holidays[3, 8] = "妇女节";
            holidays[3, 12] = "植树节";
            holidays[4, 1] = "愚人节";
            holidays[5, 1] = "劳动节"
            holidays[5, 4] = "青年节";
            holidays[5, 12] = "护士节";
            holidays[5, 14] = "母亲节";
            holidays[5, 14] = "助残日";
            holidays[6, 1] = "国际儿童节";
            holidays[6, 5] = "环境保护日";
            holidays[6, 18] = "父亲节";
            holidays[6, 26] = "国际禁毒日";
            holidays[9, 10] = "教师节";                
            holidays[11, 23] = "感恩节";
            holidays[12, 1] = "艾滋病日";                
            holidays[12, 25] = "圣诞节";
            #endregion

这是我的密码：

string holiday = holidays[e.Day.Date.Month, e.Day.Date.Day];
                    DateTime LunDay = e.Day.Date;
                    LunDay ld = new LunDay();
                    if (holiday != string.Empty)
                    {
                        //If holiday value not null,add value
                    }
                    else
                    {
                        //If holiday is null,add tradition date in carlendar
                    }

我运行代码，但它总是添加假日和不添加传统日期，如何处理it.The string.Empty没有任何影响。

以下是整个代码：

protected void portalCalendar_DayRender(object sender, DayRenderEventArgs e)
        {
            t.CurrentCulture = this.oldCulture;

            #region inital Festival
            string[,] holidays = new string[13, 32];
            holidays[1, 1] = "元旦";
            holidays[2, 14] = "情人节";
            holidays[3, 8] = "妇女节";
            holidays[3, 12] = "植树节";
            holidays[4, 1] = "愚人节";
            holidays[5, 1] = "劳动节";
            holidays[5, 4] = "青年节";
            holidays[5, 12] = "护士节";
            holidays[5, 14] = "母亲节";
            holidays[5, 14] = "助残日";
            holidays[6, 1] = "国际儿童节";
            holidays[6, 5] = "环境保护日";
            holidays[6, 18] = "父亲节";
            holidays[6, 26] = "国际禁毒日";
            holidays[7, 1] = "中共诞辰";
            holidays[8, 1] = "建军节";
            holidays[9, 10] = "教师节";
            holidays[10, 1] = "国庆节";
            holidays[11, 23] = "感恩节";
            holidays[12, 1] = "艾滋病日";
            holidays[12, 12] = "西安事变";
            holidays[12, 25] = "圣诞节";
            #endregion

            CalendarDay calDay = ((DayRenderEventArgs)e).Day;
            TableCell tableCell = ((DayRenderEventArgs)e).Cell;
            if (e.Day.IsOtherMonth)
            {
                e.Cell.Controls.Clear();
            }
            else
            {
                try
                {
                    string holiday = holidays[e.Day.Date.Month, e.Day.Date.Day];
                    DateTime LunDay = e.Day.Date;
                    LunDay ld = new LunDay();
                    if (holiday != string.Empty)
                    {

                        e.Cell.Controls.Add(new LiteralControl("<br><font color=blue size=2>" + holiday + "</font>"));
                        //e.Cell.Controls.Add(new LiteralControl("<br>" + ld.GetLunarCalendar(LunDay)));                        
                    }
                    else
                    {
                        Response.Write("null holiday"); 
                    }
                }
                catch (Exception exception)
                {
                    Response.Write(exception.ToString());
                }
            }
        }

Answer 1

奇怪的是，您的代码中有正确的注释，但是实现不正确。看看这个：

if (holiday != string.Empty)
{
     //If holiday value not null,add value
}

这里您说的是'if value null‘，但是在if条件下，您会根据空字符串检查值。空字符串与null值不相同。您还需要在代码中添加对null的检查：

if (holiday != null && holiday != string.Empty)
{
     //If holiday value not null,add value
}

这会解决你的问题。

顺便说一句，框架中也有预定义的方法来解决这个常见的场景-- string.IsNullOrEmpty()，它检查字符串和空值。