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C# 字元與字元串操作

格式化字元串:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            string Str1 = "hello lyshark";

            // 取出字元串中指定的字元
            char Str2 = Str1[1];

            Console.WriteLine("字元: {0} 轉大寫: {1} 轉小寫: {2}", Str2, Char.ToUpper(Str2), Char.ToLower(Str2));
            Console.WriteLine("是否為數字: {0} 是否為大寫: {1} 是否為小寫: {2}",
                Char.IsNumber(Str2), Char.IsUpper(Str2), Char.IsLower(Str2));

            // 将字元串轉化為字元數組
            char[] chs = Str1.ToCharArray();

            for (int x = 0; x < chs.Length - 1; x++)
                Console.Write("{0} ", chs[x]);
            Console.WriteLine();

            // 将字元數組轉化為字元串
            string Str3 = new string(chs);
            Console.WriteLine(Str3);

            // 格式化輸出字元串
            string Str4 = "hello";
            string Str5 = "lyshark";

            string new_str = String.Format("{0},{1}", Str4, Str5);
            Console.WriteLine("格式化後的字元串: {0}", new_str);

            Console.ReadKey();
        }
    }
}

比較字元串:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;


namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            string Str1 = "hello lyshark";
            string Str2 = "hello world";
            string Str3 = "hello lyshark";

            // Compare 比較字元串,相等傳回0不相等傳回-1
            Console.WriteLine("Str1 比較 Str2 " + String.Compare(Str1, Str2));
            Console.WriteLine("Str1 比較 Str3 " + String.Compare(Str1, Str3));

            // Compare To 比較字元串
            Console.WriteLine("Str1 比較 Str2 " + Str1.CompareTo(Str2));
            Console.WriteLine("Str1 比較 Str3 " + Str1.CompareTo(Str3));

            // Equals 比較字元串
            Console.WriteLine("Str1 比較 Str2 " + Str1.Equals(Str2));
            Console.WriteLine("Str1 比較 Str3 " + String.Equals(Str1,Str3));

            Console.ReadKey();
        }
    }
}

截取/分割字元串:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;


namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            // 從第一個位置開始截取3個字元
            string Str1 = "hello lyshark";
            string Str2 = "";

            Str2 = Str1.Substring(1, 3);
            Console.WriteLine("截取資料: {0}", Str2);

            // 分割字元串變量
            string Str3 = "用^一生#下載下傳,百度網盤,資源";
            char[] separator = { '^', '#', ',' };         // 定義分割字元

            String[] split_string = new String[100];
            split_string = Str3.Split(separator);

            for (int x = 0; x < split_string.Length;x++ )
            {
                Console.WriteLine("切割計數: {0} 切割字元串: {1}", x, split_string[x]);
            }

            // 針對時間的切割方法
            string str = "2019-12-12";
            char[] chs = { '-' };

            string[] date = str.Split(new char[] { '-' }, StringSplitOptions.RemoveEmptyEntries);
            Console.WriteLine("{0}年 {1}月 {2}日", date[0], date[1], date[2]);

            Console.ReadKey();
        }
    }
}

插入/删除字元串:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;


namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            // 插入字元串的示範
            string Str1 = "下載下傳";
            Str1 = Str1.Insert(0, "用一生時間");
            Console.WriteLine(Str1);

            string Str2;
            Str2 = Str1.Insert(Str1.Length, "百度網盤裡面的資源");
            Console.WriteLine(Str2);

            // 填充字元串的示範
            string Str3;
            Str3 = Str1.PadLeft(Str1.Length + 3, '*');    // 在左側填充
            Console.WriteLine("左側填充: " + Str3);
            Str3 = Str1.PadRight(Str1.Length + 3, '*');   // 在右側填充
            Console.WriteLine("右側填充: " + Str3);

            // 去空格的實作
            string str = "            hahahah          ";
            str = str.Trim();
            str = str.TrimStart();
            str = str.TrimEnd();

            // 删除字元串的示範
            Console.WriteLine("從索引3處向後删除: " + Str3.Remove(3));
            Console.WriteLine("删除指定個數的字元: " + Str3.Remove(1, 3));

            Console.ReadKey();
        }
    }
}

拷貝替換字元串:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;


namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            // 普通的拷貝字元串
            string Str1 = "hello lyshark";
            string Str2;
            Str2 = string.Copy(Str1);
            Console.WriteLine("普通拷貝: " + Str2);

            // 替換字元串
            string Str3 = "one world,one dream";
            string Str4 = Str3.Replace(',','*');
            Console.WriteLine("将,替換為** => " + Str4);

            string Str5 = Str3.Replace("one", "One");
            Console.WriteLine("将one替換為One =>" + Str5);

            Console.ReadKey();
        }
    }
}

尋找開頭結尾字元串:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;


namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            string str = "今天天氣好晴朗,處處好風光";

            // 尋找字元串開頭結尾
            if (str.StartsWith("今") && str.EndsWith("光"))
                Console.WriteLine("ok");

            // 從指定字元開始搜尋,并傳回位置
            int index = str.IndexOf("天氣", 0);
            Console.WriteLine(index);

            // 從結束位置開始搜尋
            string path = @"c:\a\b\c蒼\d\e蒼\f\g\\fd\fd\fdf\d\vfd\蒼老師.wav";
            int path_index = path.LastIndexOf("\\");
            Console.WriteLine(path_index);

            Console.ReadKey();
        }
    }
}

串聯字元串:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;


namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            // Join 将指定字元串使用|串聯起來
            string name_str = string.Join("|", "張三", "李四", "王五", "趙六", "田七");
            Console.WriteLine(name_str);

            // 将字元串切割後串聯去掉豎線
            String[] u_name = { "張三", "李四" ,"王五"};
            string ptr = string.Join("|", u_name);
            Console.WriteLine("合并後: " + ptr);

            string[] strNew = ptr.Split(new char[] { '|' }, StringSplitOptions.RemoveEmptyEntries);
            Console.WriteLine("去掉| = " + strNew[1]);

            for (int x = 0; x < strNew.Length;x++ )
                Console.WriteLine("去掉豎線 [{0}] = {1}",x,strNew[x]);
            
            Console.ReadKey();
        }
    }
}

字元串倒序輸出:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;


namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            string str = "hello lyshark";
            
            // 實作反轉字元串 hello -> olleh
            char[] chs = str.ToCharArray();

            for (int x = 0; x < chs.Length / 2;x++ )
            {
                char tmp = chs[x];
                chs[x] = chs[chs.Length - 1 - x];
                chs[chs.Length - 1 - x] = tmp;
            }
            str = new string(chs);
            Console.WriteLine("反轉後的結果: {0}", str);

            // 實作反轉單詞 hello lyshark -> lyshark hello
            string str1 = "hello lyshark";

            string[] strNew = str1.Split(new char[] { ' ' }, StringSplitOptions.RemoveEmptyEntries);
            for (int x = 0; x < strNew.Length / 2; x++)
            {
                string tmp = strNew[x];
                strNew[x] = strNew[strNew.Length - 1 - x];
                strNew[strNew.Length - 1 - x] = tmp;
            }
            str1 = string.Join(" ", strNew);
            Console.WriteLine("反轉後的結果: {0}", str1);

            Console.ReadKey();
        }
    }
}

IndexOf搜尋字元串:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;


namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            // 通過indexOf 切割特定字元
            string email = "[email protected]";
            int index = email.IndexOf("@");

            string userName = email.Substring(0, index);
            string userHost = email.Substring(index + 1);

            Console.WriteLine("名字: {0} 主機: {1}",userName,userHost);

            // 尋找指定字元出現位置
            string str = "abcd wwabcd asdcdsac waascd ascsaaa";
            int index1 = str.IndexOf('a');
            int count = 1;

            while(index1 != -1)
            {
                count++;
                index1 = str.IndexOf('a', index1 + 1);
                if (index1 == -1)
                    break;

                Console.WriteLine("第{0}次出現a的位置是{1}", count, index1);
            }

            Console.ReadKey();
        }
    }
}

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