FileStream StreamReader problem in C#

Question

I'm testing how the classes FileStream and StreamReader work togheter. Via a Console application. I'm trying to go in a file and read the lines and print them on the console.

I've been able to do it with a while-loop, but I want to try it with a foreach loop.

using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.IO;  namespace testing {     public class Program     {         public static void Main(string[] args)         {             string file = @"C:\Temp\New Folder\New Text Document.txt";             using(FileStream fs = new FileStream(file, FileMode.Open, FileAccess.Read))             {                 using(StreamReader sr = new StreamReader(fs))                 {                     foreach(string line in file)                     {                         Console.WriteLine(line);                     }                 }             }         }     } } 

The error I keep getting for this is: Cannot convert type 'char' to 'string'

The while loop, which does work, looks like this:

while((line = sr.ReadLine()) != null) {     Console.WriteLine(line); } 

I'm probably overlooking something really basic, but I can't see it.

Answer 1

If you want to read a file line-by-line via foreach (in a reusable fashion), consider the following iterator block:

    public static IEnumerable<string> ReadLines(string path)     {         using (StreamReader reader = File.OpenText(path))         {             string line;             while ((line = reader.ReadLine()) != null)             {                 yield return line;             }         }     } 

Note that this this is lazily evaluated - there is none of the buffering that you would associate with File.ReadAllLines(). The foreach syntax will ensure that the iterator is Dispose()d correctly even for exceptions, closing the file:

foreach(string line in ReadLines(file)) {     Console.WriteLine(line); } 

---

(this bit is added just for interest...)

Another advantage of this type of abstraction is that it plays beautifully with LINQ - i.e. it is easy to do transformations / filters etc with this approach:

        DateTime minDate = new DateTime(2000,1,1);         var query = from line in ReadLines(file)                     let tokens = line.Split('\t')                     let person = new                     {                         Forname = tokens[0],                         Surname = tokens[1],                         DoB = DateTime.Parse(tokens[2])                     }                     where person.DoB >= minDate                     select person;         foreach (var person in query)         {             Console.WriteLine("{0}, {1}: born {2}",                 person.Surname, person.Forname, person.DoB);         } 

And again, all evaluated lazily (no buffering).