C#使用DateAndTime.DateDiff实现计算年龄

[Microsoft.VisualBasic.CompilerServices.StandardModule]
public sealed class DateAndTime

public static long DateDiff (Microsoft.VisualBasic.DateInterval Interval, DateTime Date1, DateTime Date2, Microsoft.VisualBasic.FirstDayOfWeek DayOfWeek = Microsoft.VisualBasic.FirstDayOfWeek.Sunday, Microsoft.VisualBasic.FirstWeekOfYear WeekOfYear = Microsoft.VisualBasic.FirstWeekOfYear.Jan1);

// 使用DateDiff方法计算员工年龄
using Microsoft.VisualBasic;
 
namespace _055
{
    public partial class Form1 : Form
    {
        private GroupBox? groupBox1;
        private DateTimePicker? dateTimePicker1;
        private Label? label1;
        private Button? button1;
 
        public Form1()
        {
            InitializeComponent();
            Load += Form1_Load;
        }
        private void Form1_Load(object? sender, EventArgs e)
        {
            // 
            // dateTimePicker1
            // 
            dateTimePicker1 = new DateTimePicker
            {
                Location = new Point(104, 28),
                Name = "dateTimePicker1",
                Size = new Size(200, 23),
                TabIndex = 1
            };
            // 
            // label1
            //          
            label1 = new Label
            {
                AutoSize = true,
                Location = new Point(6, 34),
                Name = "label1",
                Size = new Size(68, 17),
                TabIndex = 0,
                Text = "选择生日："
            };
            // 
            // button1
            //           
            button1 = new Button
            {
                Location = new Point(134, 86),
                Name = "button1",
                Size = new Size(75, 23),
                TabIndex = 1,
                Text = "计算工龄",
                UseVisualStyleBackColor = true
            };
            button1.Click += Button1_Click;
            // 
            // groupBox1
            // 
            groupBox1 = new GroupBox
            {
                Location = new Point(12, 9),
                Name = "groupBox1",
                Size = new Size(310, 65),
                TabIndex = 0,
                TabStop = false,
                Text = "计算年龄："
            };
            groupBox1.Controls.Add(dateTimePicker1);
            groupBox1.Controls.Add(label1);
            groupBox1.SuspendLayout();
 
            // 
            // Form1
            // 
            AutoScaleDimensions = new SizeF(7F, 17F);
            AutoScaleMode = AutoScaleMode.Font;
            ClientSize = new Size(334, 121);
            Controls.Add(button1);
            Controls.Add(groupBox1);
            Name = "Form1";
            StartPosition = FormStartPosition.CenterScreen;
            Text = "根据生日计算员工年龄";        
            groupBox1.ResumeLayout(false);
            groupBox1.PerformLayout();
        }
        /// <summary>
        /// 计算年龄
        /// </summary>
        private void Button1_Click(object? sender, EventArgs e)
        {
            long Age = DateAndTime.DateDiff(DateInterval.Year,
                 dateTimePicker1!.Value, DateTime.Now,
                 FirstDayOfWeek.Sunday, FirstWeekOfYear.Jan1);
            MessageBox.Show(string.Format("年龄为： {0}岁。",Age.ToString()), "提示！");
        }
    }
}