一些操作字符串的方法

Compare(,)比较两个字符串

string s1 = "ahell0";

string s2 = "bhell0";
int i = string.Compare(s1, s2,ture);//true不考虑大小写，false考虑大小写
Console.Write(i);
//两个字符串比较会返回一个值1,0，-1
//两个字符串一模一样返回0；

//从前向后比较第一个不同的字符的ASCII码 s1>s2 为1，s1<s2 为-1；

Equals()比较字符串返回布尔值

string s1 = "123";
bool a = s1.Equals("12");
bool b = s1.Equals("123"); //比较字符串返回布尔值
Console.Write("{0}--{1}",a,b); //true -- false

IndexOf()与LastIndexOf()

//字符串查找 返回字符所在位置的下标
string s1 = "1238784654687546";
int a = s1.IndexOf("3");       //从前往后查找第一个字符所在的位置
int b = s1.LastIndexOf('5');   //从后往前查找第一个字符所在的位置
int c = s1.IndexOf("9");       //没有查找到返回-1
Console.Write("{0}--{1}--{2}",a,b,c); //  2 -- 13 -- -1

Insert()字符串插入新的数据

//插入新的数据
string str = "123456789";
str = str.Insert(2,"a");
Console.WriteLine(str); //  12a3456789

PadLeft()PadRight()字符前后添加字符

string myString = "Hello";
myString = myString.PadLeft(10,'a');
myString = myString.PadRight(20, 'b');
//值得注意的是前面20是整个字符串的个数
Console.WriteLine(myString);  //  aaaaaHellobbbbbbbbbb

Remove()删除字符串中的字符串

string str1 = "qewrqewrqerqwer";
int pos = str1.IndexOf("ew",0); //pos = 1;
string str2 = str1.Remove(pos,3);//(删除的位置，删除的个数)
string str3 = str2.Insert(pos,"asd");
Console.WriteLine(str1);
Console.WriteLine(str2); // qqewrqerqwer
Console.WriteLine(str3); // qasdqewrqerqwer 
Console.ReadKey();

Replace()替换字符串

string str = "123456789";
str = str.Replace("23","a");// 将字符"23"替换成"a"  检测到的第一个"23"
Console.WriteLine(str); //1a456789

Split()将字符串转成单词或在指定字符断开

string myString = "Hello my name Joshua.";
string[] myWords;
myWords = myString.Split('m');
foreach (string b in myWords) 

{
Console.WriteLine(b); //变成若干个字符串 形成一个字符串数组
}

StartWith()与EndsWith()

string s1 = "Hello my name is Joshua.";
bool a = s1.StartsWith("Hello");
bool b = s1.EndsWith("Joshua.");//对比字符串是否以这些字符开头或结尾
//返回布尔值
Console.WriteLine("{0}--{1}",a,b);

Substring()剪切字符串

string str = "123456789";
str = str.Substring(3,4);
Console.WriteLine(str); //str = 4567

ToCharArray()将字符串转成字符数组

string a = "Hello my name is Joshua.";
char[] word = a.ToCharArray();
foreach (char b in word) {

Console.Write(b);
}

ToUpper()ToLower()字符串转换成大小写

string myString = "Hello my name is Joshua.";
            myString = myString.ToUpper();
            myString = myString.ToLower();
            Console.WriteLine(myString);

Trim()去除前后多余的空格或字符

string myString = "   Hello my name is Joshua.   ";
            myString = myString.ToUpper();
            myString = myString.ToLower();
            char[] trimChar = { ' ', 'a', '.' };
            myString = myString.Trim();  //去除开头与结尾的
            myString = myString.TrimEnd(trimChar); //去除结尾的，只要包含的字符都会被去掉 结尾会变成...joshu
            myString = myString.TrimStart(); //去除开头的
            Console.WriteLine(myString);

反向打印字符串

   string myString = Console.ReadLine();
            char[] mychar = myString.ToCharArray();
            int i = myString.Length;
            foreach (char a in mychar) {
                Console.Write(a);
            }
            Console.WriteLine();
            Console.Write(i);
            Console.WriteLine();
            for (int j = i-1; j >= 0; j--) {
                Console.Write(mychar[j]);
            }

连接两个字符串

string s1 = "Hell0";
string s2 = "hell0";
string s3 = s1 + s2;
Console.Write(s3);