C#中把文件中小写英文字母转化为大写，大写字母转化为小写字母？？？？

Question

编写一个Windows应用程序，该程序功能为：从本机读取一个文本文件（文件中不包含中文字符和符号），统计文件中字符的个数，“，”个数，“.”个数。并把文件中小写英文字母转化为大写，大写字母转化为小写字母。急！！！！！！

Answer 1

string Temp = string.Empty;
string UpperTemp = string.Empty;
string LowerTemp = string.Empty;
Temp = "aBc";
UpperTemp = Temp.ToUpper();
LowerTemp = Temp.ToLower();

Answer 2

我想得到的是"AbC",就是小写字符转化为大写，大写转化为小写！都是string型的！

Answer 3

            using (StreamReader sr = new StreamReader("文本路径"))
            {
                string text = sr.ReadToEnd();
                int commaCount = 0;
                int letterCount = 0;
                int dotCount = 0;
                StringBuilder sb = new StringBuilder();
                foreach (char c in text)
                {
                    if (char.IsLetter(c))
                        letterCount++;
                    if (c == ',')
                        commaCount++;
                    if (c == '.')
                        dotCount++;
                    if (c >= 'a' && c <= 'z')
                        sb.Append(char.ToUpper(c));
                    else if (c >= 'A' && c <= 'Z')
                        sb.Append(char.ToLower(c));
                    else
                        sb.Append(c);
                }
                Console.WriteLine("字母个数为{0}", letterCount);
                Console.WriteLine(",个数为{0}", commaCount);
                Console.WriteLine(".个数为{0}", dotCount);
                Console.WriteLine("改变大小写后内容为：");
                Console.WriteLine(sb.ToString());
            }

Answer 4

StringBuilder是在哪个using里面呀？谢谢楼上的！^_^

Answer 5

using System;
using System.Text;
using System.IO;
namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            StreamReader sr = new StreamReader(args[0]);
            string text = sr.ReadToEnd();
            string outText = "";
            int total = 0;
            int dohao = 0;
            int juhao = 0;
            foreach (char c in text)
            {
                char newc = c;
                switch (c)
                {
                    case ',': dohao++; break;
                    case '.': juhao++; break;
                    default:
                        if (Char.IsLower(c))
                        {
                            newc = Char.ToUpper(c);
                        }
                        else if (Char.IsUpper(c))
                        {
                            newc = Char.ToLower(c);
                        }
                        break;
                
                }
                total++;
                outText += newc;
            }            Console.WriteLine("总字数:{0}", total);
            Console.WriteLine(" ,个数:{0}", dohao);
            Console.WriteLine(" .个数:{0}", juhao);
            Console.WriteLine("转换后:{0}", outText);
            Console.ReadLine();
        }
    }
}

Answer 6

int count0 = System.Text.RegularExpressions.Regex.Replace(yourStr, @"[^.]", "").Length;//.个数
int count1 = System.Text.RegularExpressions.Regex.Replace(yourStr, @"[^,]", "").Length;//,的个数
int count2 = System.Text.RegularExpressions.Regex.Replace(yourStr, @"[^a-z]", "").Length;//小写字母的个数
int count3 = System.Text.RegularExpressions.Regex.Replace(yourStr, @"[^A-Z]", "").Length;//大写字母的字数
int count4 = System.Text.RegularExpressions.Regex.Replace(yourStr, @"[^A-Za-z]", "").Length;//字母的个数
int count5 = System.Text.RegularExpressions.Regex.Replace(yourStr, @"[^\d]", "").Length;//数字的个数
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