using System;
using System.Globalization;
using System.Windows.Forms;

namespace WindowsFormsApplication1
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();

            var culture = CultureInfo.GetCultureInfo("ja-JP");

            this.textBox1.AppendText("小文字->大文字の順に変換したら違う文字になったもの\r\n");
            hoge(0x0000, 0xD7FF, (s) => s.ToLower(culture), (s) => s.ToUpper(culture));
            hoge(0xE000, 0xFFFF, (s) => s.ToLower(culture), (s) => s.ToUpper(culture));

            this.textBox1.AppendText("大文字->小文字の順に変換したら違う文字になったもの\r\n");
            hoge(0x0000, 0xD7FF, (s) => s.ToUpper(culture), (s) => s.ToLower(culture));
            hoge(0xE000, 0xFFFF, (s) => s.ToUpper(culture), (s) => s.ToLower(culture));
        }

        void hoge(int start, int end, Func<string, string> conv1, Func<string, string> conv2)
        {
            for (int code = start; code <= end; code++)
            {
                var s = new string((char)code, 1);
                var c1 = conv1(s);
                var c2 = conv2(c1);

                if (s != c2 && s != c1)
                {
                    textBox1.AppendText(string.Format("元の文字:{0}(U+{1:X4})->{2}(U+{3:X4})->{4}(U+{5:X4})\r\n", s, (int)s[0], c1, (int)c1[0], c2, (int)c2[0]));
                }
            }
        }
    }
}