I need make array of streamreader

Question

I want to list multiple files in a directory, and I need to merge every 10 files.

public static void MergeFiles (string pathSource)
{
    DirectoryInfo diretorio = new DirectoryInfo(pathSource);
    FileInfo[] Arquivos = diretorio.GetFiles("*.*");            
    int i = 0;

    foreach (FileInfo file in Arquivos)
    {
        StreamReader[] writer = **new StreamReader();** //'System.IO.StreamReader' does not contain a constructor that takes 0 arguments
        writer[i] = File.OpenText(diretorio + file.Name);
        Console.WriteLine(writer.Count());
        i++;
    }
}

How can I resolve this problem?

Answer 1

An array is fixed size, and should be initialized as follows (please don't call a reader "writer"):

// Size of 10
StreamReader[] writer = new StreamReader[10];

Also you are creating the array inside the loop, meaning there will be one array per file. Create the array outside of the loop:

StreamReader[] writer = new StreamReader[10];
foreach (FileInfo file in Arquivos)
{
    ...

You may consider using a List<StreamReader> so if you have say 25 files, you would be able to merge 10, 10 and finally the remaining 5 files:

List<StreamReader> readers = new List<StreamReader>();
foreach (FileInfo file in Arquivos)
{
    readers.Add(File.OpenText(diretorio + file.Name));
    if (readers.Count >= 10)
    {
        MergeFiles(readers);
        readers.Clear();
    }
}

// Optionally handle the last bunch
if (readers.Count > 0)
{
    MergeFiles(readers);
}