I want to combine three txt-files into one single file in c#

Question

Im new to C# but learning as I go forward, so forgive me if my question might be a little too easy for most of you guys. :-)

My question has two parts.

• First: I have three textfiles (with fixed names) with totaly different contents. I now want these combine into one single textfile.

• Second: During this combination process I also want every comma(,)
  in these files to be changed to a dot(.) in the output combined file.

I have managed to do something similar with StreamReader and StreamWriter in combination with ReadLine in vb but cant get it to work in C#.

Im thankful for any help I can get.

/Tomas

Answer 1

If files are not big you can use this snippet:

File.WriteAllText("newfile", String.Concat(File.ReadAllText("file1"),File.ReadAllText("file2"),File.ReadAllText("file3")).Replace(",","."));

Answer 2

In general case when files are long with arbitrary number of files you can try Linq SelectMany:

 using System.IO; 
 using System.Linq; 

 ...

 string[] fileNames = new string[] {
   @"C:\MyFile1.txt", 
   @"C:\MyFile2.txt",
   @"C:\MyFile3.txt", 
 };

 ...

 File.WriteAllLines(@"C:\MyCombinedFile.txt", fileNames
   .SelectMany(file => File.ReadLines(file))
   .Select(line => line.Replace(',', '.')));

Answer 3

string[] files = new string[]{ @"E:\myfile1.txt", @"E:\myfile2.txt", @"E:\myfile3.txt" };

        string fileContent = string.Empty;
        foreach (var fileName in files)
        {
            using (System.IO.StreamReader Reader = new System.IO.StreamReader(fileName))
            {
                fileContent += Reader.ReadToEnd();
            }
        }
        fileContent = fileContent.Replace(',', '.');

        System.IO.File.WriteAllText(@"E:\myfile.txt", fileContent);