对“C#写的简单的日历，窗体输出。”的改写，精简了一半多代码

原文：http://hi.baidu.com/wosxiaoyao/item/1837b791fde008d57b7f014f

其中的输出日历类Calendar如下：

    using System;  
    using System.Collections.Generic;  
    using System.Linq;  
    using System.Text;  
    using System.Windows.Forms;  
      
    namespace xianshirili  
    {  
        public class Calendar  
        {  
            public void PrintCalendar(int year, int month,TextBox textbox)  
            {  
                StringBuilder builder = new StringBuilder();  
                builder.Append(" 日 一 二 三 四 五 六\r\n");  
                int hawdays = GetWeeksOfDate(year, month, 1); //这个月的第一天星期几  
                int days = GetDaysOfMonth(year, month); //获取想要输出月份的天数  
                 
                for (int i = 1; i <= hawdays * 3; i++) //打印第一排前面的空格  
                {  
                    builder.Append(" ");  
                }  
                for (int j = 1; j <= days; j++)  
                {  
      
                    if (j <= 9)  
                    {  
                        builder.Append(" ");  
                        builder.Append(" ");  
                        builder.Append(Convert.ToString(j));  
                    }  
                    // Console.Write(" {0}", j);  
      
                    if (j >= 10)  
                    {  
                        builder.Append(" ");  
                        builder.Append(Convert.ToString(j));  
                    }  
                    // Console.Write(" {0}", j);  
                    if ((hawdays + j) % 7 == 0)  
                        builder.Append("\r\n");  
                }  
                 
                textbox.Text = builder.ToString();  
            }  
      
            // 计算当前日期以前的天数  
            public static int GetDaysOfDate(int year, int month, int day)  
            {  
                int days = 0;  
                for (int i = 1980; i < year; i++)  
                {  
                    days += GetDaysOfYears(i);  
                }  
                for (int i = 1; i < month; i++)  
                {  
                    days += GetDaysOfMonth(year, i);  
      
                }  
                days = days + day - 1;  
                return days;  
            }  
      
            //计算星期，返回具体的某一天星期几 值为0~6  
            public static int GetWeeksOfDate(int year, int month, int day)  
            {  
                int weeks = GetDaysOfDate(year, month, day);  
      
                return (weeks + 2) % 7;  
            }  
      
            // 判断是否闰年并返回当年总天数  
            public static bool LeapYear(int year)  
            {  
                return ((year % 4 == 0 && year % 100 != 0) || year % 400 == 0);  
            }  
      
            //判断月份，返回当月的天数  
            public static int GetDaysOfMonth(int year, int month)  
            {  
                int days = 30;  
                switch (month)  
                {  
                    case 1:  
                    case 3:  
                    case 5:  
                    case 7:  
                    case 8:  
                    case 10:  
                    case 12:  
                        days = 31; break;  
                    case 4:  
                    case 6:  
                    case 9:  
                    case 11:  
                        days = 30; break;  
                    case 2:  
                        days = LeapYear(year) ? 29 : 28; break;  
                    default:  
                        days = 30; break;  
                }  
                return days;  
            }  
      
            //根据年，判断是否闰年并返回一年里有几天  
            public static int GetDaysOfYears(int year)  
            {  
                return LeapYear(year) ? 366 : 365;  
            }  
        }  
    }  

 经过一翻改写测试，最终实现同样的功能，代码精简了一半多，如下：

    using System;  
    using System.Collections.Generic;  
    using System.Linq;  
    using System.Text;  
    using System.Windows.Forms;  
      
    public class Calendar  
    {  
        public void PrintCalendar(int year, int month, TextBox textbox)  
        {  
            StringBuilder builder = new StringBuilder();  
            builder.Append(" 日 一 二 三 四 五 六\r\n");  
            int hawdays = GetWeeksOfDate(year, month, 1); //这个月的第一天星期几  
            int days = GetDaysOfMonth(year, month); //获取想要输出月份的天数  
      
            for (int i = 1; i <= hawdays * 3; i++) //打印第一排前面的空格  
            {  
                builder.Append(" ");  
            }  
            for (int j = 1; j <= days; j++)  
            {  
                builder.Append(j.ToString().PadLeft(3, ' '));  
              
                if ((hawdays + j) % 7 == 0)  
                    builder.Append("\r\n");  
            }  
            textbox.Text = builder.ToString();  
        }  
          
        //计算星期几: 星期日至星期六的值为0-6  
        public static int GetWeeksOfDate(int year, int month, int day)  
        {  
            DateTime dt = new DateTime(year, month, day);  
            DayOfWeek d = dt.DayOfWeek;  
            return Convert.ToInt32(d);  
        }  
        //获取指定年月的天数  
        public static int GetDaysOfMonth(int year, int month)  
        {  
            DateTime dtCur = new DateTime(year, month, 1);  
            int days = dtCur.AddMonths(1).AddDays(-1).Day;  
            return days;  
        }    
    }