程序代码：

namespace p118_3
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            DateTime dt1 = Convert.ToDateTime(textBox1.Text);
            DateTime dt2 = Convert.ToDateTime(textBox2.Text);
            TimeSpan ts1 = dt2.Subtract(dt1);
            int countday = ts1.Days;
            int weekday = 0;
            for (int i = 0; i < countday; i++) ;
            DateTime tempdt = dt1.Date.AddDays(1);
            if (tempdt.DayOfWeek != System.DayOfWeek.Saturday && tempdt.DayOfWeek != System.DayOfWeek.Sunday) 
            {
                weekday++;
            }
            label4 .Text = string .Format ("{0:D}到{0:D}之间的工作日共有{1}天",dt1 ,dt2 ,weekday );
        }



        }

      
    }