字符串常用操作

1.比较字符串：Compare、CompareTo、Equals、==、！=
2.定位字符和子串：StartWith/EndsWith、IndexOf/LastIndexOf、IndexOfAny/LastIndexOfAny
3.格式化字符串：Format
4.连接字符串：Concat、Join、+
5.分裂字符串：Split
6.插入和填充字符串：Insert、PadLeft/PagRight
7.删除和剪切字符串：Remove、Trim/TrimStart/TrimEnd
8.复制字符串：Copy、CopyTo
9.替换字符串：Replace
10.更改大小写：ToUpper/ToLower

        Console.WriteLine( " -------------------test Join  " );
            String str  =   "" ;
            String[] strArr  =  {  " aaa " ,  " bbb " ,  " ccc "  };
            str  =  String.Join( " + " , strArr);
            Console.WriteLine(str);  // str="aaa+bbb+ccc"

            Console.WriteLine( " -------------------test Format " );
            String strA  =   " Hello " ;
            String strB  =   " World " ;
            str  =  String.Format( " {0},{1}! " , strA, strB);
            Console.WriteLine(str);

            Console.WriteLine( " -------------------test CompareTo " );
            Console.WriteLine(strA.CompareTo(strB)); // -1
        Console.WriteLine( " abc " .CompareTo( " abc " )); // 0
        Console.WriteLine( " abc " .CompareTo( " abcded " )); // -1
        Console.WriteLine( " abcde " .CompareTo( " abc " )); // 1
         Console.WriteLine( string .Compare( " abc " ,  " abc " ));  // 0
        Console.WriteLine( string .Compare( " abdddc " ,  " abc " )); // 1 
        Console.WriteLine( string .Compare( " abd " ,  " abcdd " ));  // -1
            Console.WriteLine( " -------------------test IndexOf " );
            Console.WriteLine(str.IndexOf( ' l ' ));
         char  [] aaa = { ' e ' , ' H ' , ' o ' };
            Console.WriteLine(str.IndexOfAny(aaa));   // aaa里的任意字符与str中第一个匹配项的索引,结果为0
        Console.WriteLine(str.LastIndexOfAny(aaa));  // aaa里的任意字符与str中最后一个匹配项的索引,结果为1
            Console.WriteLine( " -------------------test Split " );
            strArr  =  str.Split( ' , ' );  // 分裂字符串 结果为：strArr[0]=hello  strArr[1]=world
             int  i  =   0 ;
             while  (i  <  strArr.Length)
            {
                Console.WriteLine(strArr[i]);
                i ++ ;
            }

            Console.WriteLine( " -------------------test PadLeft " );
            str  =   " hello " ;
            str  =  str.PadLeft( 20 ,  ' * ' );  // 20为填充后的字符串总长度
        str  =  str.PadLeft( 20 ,  ' * ' );
            Console.WriteLine(str);

            Console.WriteLine( " -------------------test Remove " );
            str  =   " abcdefg " ;
            str  =  str.Remove( 1 ,  3 );
            Console.WriteLine(str);

            Console.WriteLine( " -------------------test Trim " );
            str  =   " %hello&$# " ;
             char [] trmchar  = {  ' % ' ,  ' & ' ,  ' $ ' ,  ' # '  };
            str  =  str.Trim(trmchar);
        str  =  str.TrimStart(trmchar);  // 只删除开始的trmchar 值，结果为hello&$#
        str  =  str.TrimEnd(trmchar);  // 只删除末尾的trmchar 值，结果为%hello
             string  str1 = string .Copy(str);
            Console.WriteLine(str);