字符串比较

namespace demo1
{internal class progrm{static void Main(string[] args){string str = "hello world";Console.WriteLine("大写字符{0}",str.ToUpper());Console.WriteLine("小写字符{0}",str.ToLower());Console.WriteLine("字符长度{0}", str.Length);//字符串的比较，按照字典的排序，判定两个字符的相对大小//方法1 compare，返回的结果大于0，则说明大于string a = "hello";string b = "world";int c=string.Compare(a,b);//Console.WriteLine(c);if (c > 0){Console.WriteLine("c={0} a>b",c);}else {Console.WriteLine("c={0},a<b",c); }//方法2 Compare To ,不是静态方法，通过string对象调用int d=a.CompareTo(b);Console.WriteLine(d);//方法 Equals  判断两个字符串是否相等bool e=a.Equals(b);Console.WriteLine(e);bool f=String.Equals(a,b);Console.WriteLine(f);}}  
}

字符串格式化

namespace demo1
{internal class progrm{static void Main(string[] args){//字符串格式化for (int i = 0;i<10;i++){string str = String.Format("{0:E}",i);Console.WriteLine(str);}for (int i = 0; i < 10; i++){string str = String.Format("{0:C}", i);Console.WriteLine(str);}for (int i = 0; i < 10; i++){string str = String.Format("{0:P}", i);Console.WriteLine(str);}for (int i = 0; i < 10; i++){string str = String.Format("{0:X}", i);Console.WriteLine(str);}}}  
}

字符串常用操作

namespace demo1
{internal class progrm{static void Main(string[] args){//字符串截取Console.WriteLine("字符串截取");string str = "hello world";string s1=str.Substring(1,8);Console.WriteLine(s1);//字符串的分割Console.WriteLine("字符串的分割");string[] s2=str.Split(' ');foreach(string i in s2){Console.WriteLine(i);}//Console.WriteLine(s2);//字符串的合并Console.WriteLine("字符串合并");string str1 = "hello";string str2 = "world";Console.WriteLine(str1+str2);Console.WriteLine(string.Join("_", str1,str2));Console.WriteLine(string.Concat(str1,str2));//字符串的插入Console.WriteLine("字符串的插入");string str3 = "孙";string str4 = str1.Insert(str1.Length, str3);Console.WriteLine(str4);//字符串的填充Console.WriteLine("字符串的填充");string str5=str1.PadRight(20,' ');Console.WriteLine(str5);Console.WriteLine(str5.Length);//字符串的删除Console.WriteLine("字符串的删除");string str6=str1.PadRight(20,'h');string str7=str6.Remove(5);Console.WriteLine(str7);//字符串的修剪//Trim删除首尾空格//TrimStart 删除头部空格//TrimEnd  删除尾部空格string str8 = " hello world ";Console.WriteLine(str8.Trim());Console.WriteLine(str8.TrimStart());Console.WriteLine(str8.TrimEnd());//字符串的复制string str9;str9 = string.Copy(str8);Console.WriteLine(str9);char[] str10=new char[10];str8.CopyTo(0, str10,0,1);Console.WriteLine(str10);//字符串的替换string oldstr = "www.hao123";Console.WriteLine("替换前的字符串{0}",oldstr);string newstr = oldstr.Replace('w', 'W');Console.WriteLine("替换后的{0}", newstr);//字符串的查找//IndexOf 查找字符串中字符首次出现的位置，并返回首索引位置//LastIndexOf 从后向前定位字符，并返回最后一次的位置string str12 = "good morning,everyone";Console.WriteLine(str12);int a=str12.IndexOf("g");Console.WriteLine(a);int b =str12.LastIndexOf("o");Console.WriteLine(b);}}  
}