C#实现将日期格式化为指定格式

DateTime.Now.ToString("yyyy ");
DateTime.Now.ToString("MM");
DateTime Now.ToString("dd");
DateTime.Now.ToString("HH");
Date Time.Now.ToString("mm");
DateTime.Now.ToString("ss");

// DateTime.Now.ToString()
// 使用指定格式的字符串变量格式化日期字符串
namespace _061
{
    public partial class Form1 : Form
    {
        private GroupBox? groupBox1;
        private Label? label1;
        private Button? button1;
 
        public Form1()
        {
            InitializeComponent();
            Load += Form1_Load;
        }
        private void Form1_Load(object? sender, EventArgs e)
        {
            // 
            // button1
            // 
            button1 = new Button
            {
                Location = new Point(103, 22),
                Name = "button1",
                Size = new Size(75, 23),
                TabIndex = 0,
                Text = "开始转化",
                UseVisualStyleBackColor = true
            };
            button1.Click += Button1_Click;
            // 
            // label1
            // 
            label1 = new Label
            {
                AutoSize = true,
                ImageAlign = ContentAlignment.TopLeft,
                Location = new Point(6, 45),
                Name = "label1",
                Size = new Size(56, 17),
                TabIndex = 1,
                Text = "显示内容"
            };
            // 
            // groupBox1
            // 
            groupBox1 = new GroupBox
            {
                Location = new Point(12, 12),
                Name = "groupBox1",
                Size = new Size(300, 183),
                TabIndex = 0,
                TabStop = false,
                Text = "日期格式转指定格式"
            };
            groupBox1.Controls.Add(label1);
            groupBox1.Controls.Add(button1);
            groupBox1.SuspendLayout();
           
            // 
            // Form1
            // 
            AutoScaleDimensions = new SizeF(7F, 17F);
            AutoScaleMode = AutoScaleMode.Font;
            ClientSize = new Size(324, 206);
            Controls.Add(groupBox1);
            Name = "Form1";
            StartPosition = FormStartPosition.CenterParent;
            Text = "将日期格式转化为指定的格式";           
            groupBox1.ResumeLayout(false);
            groupBox1.PerformLayout();
        }
        /// <summary>
        /// DateTime.Now.ToString()
        /// 使用指定格式的字符串变量格式化日期字符串
        /// </summary>
        private void Button1_Click(object? sender, EventArgs e)
        {
            label1!.Text =
                DateTime.Now.ToString("d") + "\n" +
                DateTime.Now.ToString("D") + "\n" +
                DateTime.Now.ToString("f") + "\n" +
                DateTime.Now.ToString("F") + "\n" +
                DateTime.Now.ToString("g") + "\n" +
                DateTime.Now.ToString("G") + "\n" +
                DateTime.Now.ToString("R") + "\n" +
                DateTime.Now.ToString("y") + "\n" +
                "当前系统时间为：" + DateTime.Now.ToString(//使用自定义格式格式化字符串
                "yyyy年MM月dd日 HH时mm分ss秒");
        }
    }
}