void Main()
{
    for(var day=new DateTime(2012,2,1);day<new DateTime(2012,3,1).AddDays(-1);day=day.AddDays(1))
    {
      Console.WriteLine(day.ToString("yyyy-MM-dd"));
    }
    /*
    2012-02-01
2012-02-02
2012-02-03
2012-02-04
2012-02-05
2012-02-06
2012-02-07
2012-02-08
2012-02-09
2012-02-10
2012-02-11
2012-02-12
2012-02-13
2012-02-14
2012-02-15
2012-02-16
2012-02-17
2012-02-18
2012-02-19
2012-02-20
2012-02-21
2012-02-22
2012-02-23
2012-02-24
2012-02-25
2012-02-26
2012-02-27
2012-02-28
    */
}

------解决方案--------------------
探讨

C# code

void Main()
{
    for(var day=new DateTime(2012,2,1);day<new DateTime(2012,3,1).AddDays(-1);day=day.AddDays(1))
    {
      Console.WriteLine(day.ToString("yyyy-MM-dd"));
    }
    /*……


------解决方案--------------------

	for(var day=new DateTime(2012,2,1);day<=new DateTime(2012,3,1).AddDays(-1);day=day.AddDays(1))

------解决方案--------------------
探讨

DateTime.DaysInMonth，取得总天数，然后从1号开始循环