前言：記得我們老師說過一句話，對字符串的學習程度就是當別人打你一拳你知道痛的情況，所以字符串的處理我們必須學的差不多，這幾篇博客完全是我的學習過程中記錄的筆記，在這里分享一下讓很多剛開始學習.net編程的人能夠很快的學會怎么處理字符串
- string的構造方法
(1) String和string意思一樣，只是String是.net FrameWork提供的，而string是C#語言提供的
?(2)字符串是不可變的? ??
class Program
{static void Main(string[] args){string str = "123456";(*)string s1 = new string(new char[] { '我', '是', '韓', '迎', '龍' }); //輸出字符串(*)string s2 = new string('0', 10); //輸出10個0Console.WriteLine(s1);Console.WriteLine(s2);Console.WriteLine(5.ToString("00000")); //前面補0string str1 = "韓閃閃";char[] chs = str1.ToCharArray();for (int i = 0; i < chs.Length; i++){if (chs[i] == '閃'){chs[i] = '珊';}}str1 = new string(chs);Console.WriteLine(str1);Console.ReadKey();}}- 字符串的方法和常量
(1) 字符串賦初值的三種方法
???? string str = "";
???? string str1 = string.Empty;
???? string str2 = null;
(2)判斷字符串是否為空
???? Console.WriteLine(string.IsNullOrEmpty(string.Empty));
(3)字符串拘留池(駐留池)
???? 使用字符串的時候，如果字符串相同，那么所有變量都指向同一個地方
(4)字符串的比較方法
???? 1)比較兩個字符串可以使用==或者Equals
???? 2)Equals的使用
???? ?????? ->靜態版本? string.Equals(object objA,object objB[,StringComparison com]);
???? ?????? ->實例版本? str.Equals(object objA);
???? 3)一個靜態的方法 Compare
???? ?????? ->string.Compare(str1,str2)
??????????? ?????? str1>str2?? 1
??????????? ?????? str1=str2?? 0
?????????????????? str1<str2?? -1
(5)全部轉換為小寫，或者大寫? ToLower,ToUpper
???? string str="assdfdSDS";
???? str=str.ToUpper();
???? Console.WriteLine(str); //全部變成大寫輸出
(6)去掉兩端的空格和指定的元素
???? string str=" 1234343 ";
???? str=str.Trim();
???? 1)Trim(params char[] chs)
????????????? string str = "? 11154544dfddf4351111? ";
??? ???str = str.Trim(' ', '1');
????? ?Console.WriteLine(str);
??? ??//輸出結果:54544dfddf435
(7)字符串的合并和分隔
???? 1)合并
???? ?????? string[] str = { "韓迎龍", "李瀟絮", "小李飛刀" };
???? ?????? string s = string.Join("|", str);
???? ?????? Console.WriteLine(s);
???? ?????? Console.ReadKey();
???? 2)分隔
???? ?????? 語法：
???? ????????????? string[] <string>.Split(params char[] chs)
??????????? ?????? string[] <string>.Split(new char[] chs,StringSplitOptions.RemoveEmpty)
?????????????????? string s = "韓迎龍|23|男|女";
?????????????????? string[] str = s.Split('|');
?????????????????? Console.ReadKey();
(8)判斷字符串的長度
???? 1)語法：<string>.Length;
???? 2)字符串可以像數組一樣使用"下標"訪問(索引)
??????????? for(int i=0;i<str.Length;i++)
??????????? {
?????????????????? Console.WriteLine(str[i]);
??????????? }
(9)字符串查找
???? 1)判斷是否包含 Contains
??????????? ->語法：bool <string>.Contains(string str);
string str = "張三，韓迎龍，李四，王五，馬六，楊七";if (str.Contains("韓迎龍")){Console.WriteLine("查找到了");}else{Console.WriteLine("沒找到");}??????????? ->模擬Contains的實現(很局限)
static bool MyContains(string src, char cmp){bool isTrue = false;for (int i = 0; i < src.Length; i++){if (src[i] == cmp){isTrue = true;break;}}return isTrue;}???? 2)IndexOf 尋找索引
??????????? ->語法：
?????????????????? int <string>.IndexOf(char ch);
?????????????????? int <string>.IndexOf(char ch[,int startIndex]);
?????????????????? int <string>.IndexOf(string str[,int startIndex]);
????????????????????????? string str = " 好好學習，天天向上";
????????????????????????? int indeof = str.IndexOf('向');
??????????? ->模擬MyIndex的算法(很局限)? ? ? ? ? ? ? ? ? ?
static int MyIndex(string src, char cmp){int index = -1;for (int i = 0; i < src.Length; i++){if (src[i] == cmp){index = i;break;}}return index;}???? 3)找出字符串中所有的"e"??
static void Main(string[] args){string str = "asfseeefsafserefeefsde";int index = -1;do{index = str.IndexOf('e', index + 1);if (index != -1){Console.WriteLine(index);}} while (index != -1);} (10)LastIndexOf 從右邊往左邊找
???? ?string str = "32errrwefsfsd";
??? int index = str.LastIndexOf('e'); //輸出7
(11)子字符串
???? 1)語法：string <string>.SubString(開始的索引，字符串的長度);
???? ????????????? string <string>.SubString(開始的索引);
???? 2)案例：
???? ?????? string str = @"F:\heima\practice\string.exe";
?? ????int start = str.IndexOf('\\');
????? ?int length = str.IndexOf('\\', start + 1) - start;
?????? string s = str.Substring(start + 1, length - 1);
???? 3)跑馬燈的效果? ? ? ? ?
string str = "北京歡迎您 ";while (true){Console.Clear();str = str.Substring(1) + str.Substring(0, 1);Console.WriteLine(str);System.Threading.Thread.Sleep(200);}字符串的插入，移除，替換
????????????? 1)insert
???????????????????? string str = "時間就是一把殺豬刀啊";
??????????? str = str.Insert(0, "世界上");
????????????? 2)remove
???????????????????? string str = "時間就是一把殺豬刀啊";
??????????? str = str.Remove(0, 2);
????????????? 3)replace
???????????????????? string str = "時間就是一把殺豬刀啊";
??????????? str = str.Replace("時間", "小賢");
?????? (13)判斷結束和開始
????????????? 1)判斷字符<string>串是否已某字符串開始或結束
????????????? 2)bool <string>.StartsWith(string str);
????????????? 3)bool <string>.EndsWith(string str);? ? ? ? ? ? ?
1)第一個案例string[] str = {"白天不懂夜的黑.mp3","夢想的力量.mp3","舊夢重彈.wma","我相信.mp3" };for (int i = 0; i < str.Length; i++){if (str[i].EndsWith(".mp3")){Console.WriteLine(str[i] + "下載成功");}else{Console.WriteLine(str[i] + "格式不正確");}}2)第二個案例static void Main(string[] args){string path1= "http://www.cnblogs.com";string path2 = "http://www.cnblogs.com/";string file = "舊夢重彈.mp3";string downfile = GetFileName(path1, file);Console.WriteLine(downfile);Console.ReadKey();}static string GetFileName(string path, string file){if (path.EndsWith("/")){return path + file;}else{return path + '/' + file;}}(14)字符串的幾個練習題
?1)接收用戶輸入的字符串，將其中的字符以相反的順序輸出"韓迎龍"->"龍迎韓"
static void Main(string[] args){string str = "韓迎龍";//第一種寫法for (int i = str.Length-1; i >=0; i--){Console.Write(str[i] );}//第二種寫法string strname = Exercise(str);Console.WriteLine(strname);}static string Exercise(string str){char[] chs = str.ToCharArray(); //變成char數組for (int i = 0; i < chs.Length / 2; i++){char temp = chs[i];chs[i] = chs[chs.Length - i - 1];chs[chs.Length - i - 1] = temp;}return new string(chs);}? 2)接受用戶輸入的一句英文，將其中的單詞反序輸出。"I Love you"->"I evol uoy"
static void Main(string[] args){string str = "I Love You";str = Exercise(str);Console.WriteLine(str);}static string Exercise(string str){string[] strs = str.Split(new char[] { ' ' }, StringSplitOptions.RemoveEmptyEntries);for (int i = 0; i < strs.Length; i++){strs[i] = Exercisetwo(strs[i]);}return string.Join(" ", strs);}static string Exercisetwo(string str){char[] chs = str.ToCharArray(); //變成char數組for (int i = 0; i < chs.Length / 2; i++){char temp = chs[i];chs[i] = chs[chs.Length - i - 1];chs[chs.Length - i - 1] = temp;}return new string(chs);}? 3)"2012年12月21日"從日期字符串中把年月日分別取出來，打印到控制臺? ? ?
static void Main(string[] args){string str = "2012年10月03日";string[] strs = str.Split(new char[] { '年', '月', '日' });Console.WriteLine(string.Join(" ", strs));Console.ReadKey();}? 4)把csv文件中的聯系人的姓名和電話顯示出來，簡單模擬
? ? 注:首先將一個name.txt結構的文檔放在項目的Bin的Debug目錄下面，使其代碼能夠讀到這個,里面的結構是"韓迎龍|男|23"
static void Main(string[] args){string[] lines = File.ReadAllLines("name.txt");for (int i = 0; i < lines.Length; i++){string[] strTemp = lines[i].Split(new char[] { '|' }, StringSplitOptions.RemoveEmptyEntries);Console.WriteLine("姓名:{0},年齡:{1}", strTemp[0], strTemp[2]);}})
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