C#中迭代器和分部类的使用

//迭代器
using System.Collections;
namespace _01
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            groupBox1.Text = "测试迭代器";

            Family myfamily = new();            //实例化Family
            foreach (string str in myfamily)    //遍历输出myfamily
            {
                richTextBox1.Text += str + "\n";
            }
        }

        /// <summary>
        /// 创建一个名为Family的类，其继承IEnumerable接口，
        /// 该接口公开枚举数，该枚举数支持在非泛型集合上进行简单迭代。
        /// 对IEnumerator接口实现GetEnumerator()方法创建迭代器
        /// </summary>
        public class Family : IEnumerable
        {
            readonly string[] MyFamily = { "父亲", "母亲", "弟弟", "妹妹" };
            public IEnumerator GetEnumerator()
            {
                for (int i = 0; i < MyFamily.Length; i++)
                {
                    yield return MyFamily[i];   //迭代器返回数组元素
                }
            }
        }
    }
}

//分部类
namespace _02
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            groupBox1.Text = "四则运算：";
            button1.Text = "等于";
            label1.Text= "运算结果：";
                    
            label1.AutoSize = true;
            button1.Size = new Size(65, 23);
            textBox1.Size = new Size(75, 23);
            textBox2.Size = new Size(70, 23);
            textBox3.Size = new Size(205, 23);
            comboBox1.Size = new Size(35, 23);

            comboBox1.Items.AddRange(["加", "减", "乘", "除"]);
            comboBox1.SelectedIndex = 0;
            comboBox1.DropDownStyle = ComboBoxStyle.DropDownList;           
        }

        private void Button1_Click(object sender, EventArgs e)
        {
            try
            {
                Account at = new();
                int M = int.Parse(textBox1.Text.Trim());    //操作数1
                int N = int.Parse(textBox2.Text.Trim());    //操作数2
                string str = comboBox1.Text;
                switch (str)
                {
                    case "加": textBox3.Text = Account.Addition(M, N).ToString(); break;
                    case "减": textBox3.Text = Account.Subtration(M, N).ToString(); break;
                    case "乘": textBox3.Text = Account.Multiplication(M, N).ToString(); break;
                    case "除": textBox3.Text = Account.Division(M, N).ToString(); break;
                }
            }

            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
            }
        }

        #region 加减乘除
        partial class Account							    //分部类第1部分
        {
            public static int Addition(int a, int b)       
            {
                return (a + b);							    //加法
            }
        }
        partial class Account								//分部类第2部分
        {
            public static int Multiplication(int a, int b)	
            {
                return (a * b);								//乘法
            }
        }
        partial class Account                               //分部类第3部分
        {
            public static int Subtration(int a, int b)      
            {
                return (a - b);                             //减法
            }
        }
        partial class Account                               //分部类第4部分
        {
            public static double Division(int a, int b)
            {                
                return ((double)a / b);                     //除法
            }
        }
        #endregion 加减乘除
    }
}