พอดีอยากให้ตัวนี้คำนวนนาทีให้ด้วยค่ะ แต่เขียนแบบนี้คำนวณแค่รวมเป็นชั่วโมงให้ไม่นับนาที ถ้าอยากให้นับนาทีด้วยต้องเขียนยังไงบ้างค่ะ การคำนวณเวลาโดยรวมเป็นชั่วโมงและนาทีด้วย C#

//เปลี่ยน format เป็น time ด้วยนะครับ
//this.dateTimePicker1.Format = System.Windows.Forms.DateTimePickerFormat.Time;
 this.Text = new DateTime((dateTimePicker2.Value - dateTimePicker1.Value).Ticks).ToString("hh:mm:ss");

 this.dateTimePicker1.CustomFormat = "hh:mm:ss tt";
this.dateTimePicker1.Format = System.Windows.Forms.DateTimePickerFormat.Custom;

 // dateTimePicker1
            // 
            //this.dateTimePicker1.Format = System.Windows.Forms.DateTimePickerFormat.Time;
            this.Text = new System.DateTime((dateTimePicker2.Value - dateTimePicker1.Value).Ticks).ToString("hh:mm:ss");
            this.dateTimePicker1.Location = new System.Drawing.Point(39, 40);
            this.dateTimePicker1.Name = "dateTimePicker1";
            this.dateTimePicker1.Size = new System.Drawing.Size(108, 20);
            this.dateTimePicker1.TabIndex = 127;

public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
            this.dateTimePicker1.CustomFormat = "hh:mm:ss tt";
            this.dateTimePicker1.Format = System.Windows.Forms.DateTimePickerFormat.Custom;
            this.dateTimePicker2.CustomFormat = "hh:mm:ss tt";
            this.dateTimePicker2.Format = System.Windows.Forms.DateTimePickerFormat.Custom;
        }

        private void button1_Click(object sender, EventArgs e)
        {
            TimeSpan t = dateTimePicker1.Value - dateTimePicker2.Value;
            DateTime d1 = dateTimePicker1.Value;
            DateTime d2 = dateTimePicker2.Value;

            richTextBox1.Text += Environment.NewLine + "dateTimePicker2.Value - dateTimePicker1.Value = " + d2.ToString() + "-" + d1.ToString() + "= " + (dateTimePicker2.Value - dateTimePicker1.Value);
            richTextBox1.Text += Environment.NewLine;
            richTextBox1.Text += Environment.NewLine + "dateTimePicker1.Value - dateTimePicker2.Value = " + d1.ToString() + "-" + d2.ToString() + "= " + (dateTimePicker1.Value - dateTimePicker2.Value);

           this.Text = new DateTime(System.Math.Abs((dateTimePicker1.Value - dateTimePicker2.Value).Ticks)).ToString("hh:mm:ss");
        }
    }

            string d1 = DateTime.Now.ToShortDateString();
            string d2 = DateTime.Now.ToShortDateString();
            d1 = d1 + " 01:20:10";
            d2 = d2 + " 23:50:59";
            dateTimePicker1.Value = DateTime.Parse(d1);
            dateTimePicker2.Value = DateTime.Parse(d2);
            DateTime date1 = dateTimePicker1.Value;
            DateTime date2 = dateTimePicker2.Value;


private void button1_Click(object sender, EventArgs e)
        {
            TimeSpan ts = dateTimePicker2.Value - dateTimePicker1.Value;
            this.Text = new DateTime(ts.Ticks).ToString("HH:mm:ss");
        }