How to Change the name of a Text File in a loop using visual c# and streamwriter

Question

I am trying to write a loop that reads through a list, and saves parts of that list to different text files based on the hour the data was taken. I want to name the text file based on the hour that the data was taken.

Here is the relevant code:

private StreamWriter filename;
string[] hour = {"00","01","02","03","04","05","06","07","08","09","10","11","12","13","14","15","16","17","18","19","20","21","22","23}

private void btn_hourfiles_click(object sender, EventArgs e)
{
    int sizeoflist = Data_List.Count(); //This is the list containing the data
    for (int i = 0; i<sizeoflist,i++)
    {
       string[] listsplit = Data_List[i].Split(":");
       for (int j = 0; j<24; j++)
       {
           if (listsplit[2] == hour[j])
           {
            string[] datesplit = txt_DATE.Text.Split('-');//splits input date
            filename = datesplit[0] + '_' + dateplit[1] + '_' + datesplit[2] + '_' + hour[j] + '.dat'
            filename = new StreamWriter(new FileStream(Data_List[i], FileMode.Append, FileAccess.Write));
            }
       }
    }
 }

The problem: I can't change the StreamWriter filename. I get an error that says: Cannot implicitly convert type string to System.IO.StreamWriter

Question: How can I change the variable filename?

Answer 1

The code you post is not getting compiled. Try next time to post the input so it will be simpler to help and answer to your question. Anyway, I tried to help you according to what you wrote above, hope it will help you

class Program {

    static void Main(string[] args)
    {
        MyTest test = new MyTest();

        test.Foo();
    }
}

class MyTest
{
    private StreamWriter streamWriter;
    string[] hour = { "00", "01", "02", "03", "04", "05", "06", "07", "08", "09", "10", "11", "12", "13", "14", "15", "16", "17", "18", "19", "20", "21", "22", "23" };

    public void Foo()
    {
        string txt_DATE = "25-02-2015";
        string[] Data_List = { "12:05:10", "02:15:00", "14:15:22" };

        int sizeoflist = 3; // Data_List.Count(); //This is the list containing the data
        for (int i = 0; i < sizeoflist; i++)
        {
            string[] listsplit = Data_List[i].Split(':');
            for (int j = 0; j < 24; j++)
            {
                if (listsplit[2] == hour[j])
                {
                    string[] datesplit = txt_DATE.Split('-');//splits input date
                    var filename = datesplit[0] + '_' + datesplit[1] + '_' + datesplit[2] + '_' + hour[j] + ".dat";
                    streamWriter = new StreamWriter(new FileStream("C:\\" + filename, FileMode.Append, FileAccess.Write));
                }
            }
        }
    }
}

Answer 2

The problem is that StreamWriter is declared thusly:

private StreamWriter filename;

but then assigned a string:

filename = datesplit[0] + '_' + dateplit[1] + '_' + datesplit[2] + '_' + hour[j] + '.dat'

Suggestion: use separate variables for filename and for the StreamWriter.