Alphabetize using I/O in C# -

i'm trying use i/o , sort input file alphabetically using method called alphabetize, has compile error

(35,42): error cs1061: 'string' not contain definition 'toarray' , no extension method 'toarray' accepting first argument of type 'string' found (are missing using directive or assembly reference?)

what can resolve that?

using system; using system.io;  namespace examplefile {     class examplefile     {         static void main(string[] args)         {              streamwriter writer = null;              writer = new streamwriter(@"c:\c#files\outputwrite2.txt");              console.setout(writer);              console.setin(new streamreader(@"c:\c#files\inputread2.txt"));              string letters;             while ((letters = console.readline()) != null)             writer.close();               streamwriter standardoutput = new streamwriter(console.openstandardoutput());             standardoutput.autoflush = true;             console.setout(standardoutput);              console.writeline("sorted letters alphabetically , wrote output file.");          }          public static string alphabetize(string letters)         {             char[] alphabetize = letters.toarray();             array.sort(alphabetize);             return new string(alphabetize);         }     } } 

your problem here:

char[] alphabetize = letters.toarray(); 

as error got states:

'string' not contain definition 'toarray' , no extension method 'toarray' accepting first argument of type 'string' found

there 2 parts error message. first part says string doesn't have toarray() method. since letters string, can't call toarray() on it. try instead:

char[] alphabetize = letters.tochararray(); 

the second part of error tells there no toarray extension method defined in context; however, system.linq namespace has extension method toarray<tsource>() on interface ienumerable<char>. string implements ienumerable<char>, if include system.linq namespace in file, can call extension method toarray<tsource>():

// @ top of file other includes. using system.text;  // can this: char[] alphabetize = letters.toarray();