write file name with parameter inside for loop

Question

I want to create a list with all the numbers between 0000000 - 9999999 and to create a new file every 50000 rows.

I tried this code:

using (System.IO.StreamWriter file = new System.IO.StreamWriter(@"E:\numbers" + fileparam + ".txt"))
{
    for (counter = 0 ; counter < 10000000 ; counter++)
    {
        if (counter < 10)
        {
            file.WriteLine("000000" + counter.ToString());
        }
        else if (counter > 9 && counter < 100)
        {
            file.WriteLine("00000" + counter.ToString());
        }
        else if (counter > 99 && counter < 1000)
        {
            file.WriteLine("0000" + counter.ToString());
        }
        else if (counter > 999 && counter < 10000)
        {
            file.WriteLine("000" + counter.ToString());
        }
        else if (counter > 9999 && counter < 100000)
        {
            file.WriteLine("00" + counter.ToString());
        }
        else if (counter > 99999 && counter < 1000000)
        {
            file.WriteLine("0" + counter.ToString());
        }
        else if (counter > 999999 && counter < 10000000)
        {
            file.WriteLine(counter.ToString());
        }
        if (counter % 50000 == 0)
        {
            fileparam++;
        }
    }
}

but it didn't work, because it already opened with the "fileparam" that was initialized at the start of the program "int fileparam = 0;" and i got "numbers0.txt"

I also tried this:

using (System.IO.StreamWriter file = new System.IO.StreamWriter(@"E:\numbers" + fileparam + ".txt"))
{
    for (counter = 0 ; counter < 10000000 ; counter++)
    {
        if (counter < 10)
        {
            file.WriteLine("000000" + counter.ToString());
        }
        else if (counter > 9 && counter < 100)
        {
            file.WriteLine("00000" + counter.ToString());
        }
        else if (counter > 99 && counter < 1000)
        {
            file.WriteLine("0000" + counter.ToString());
        }
        else if (counter > 999 && counter < 10000)
        {
            file.WriteLine("000" + counter.ToString());
        }
        else if (counter > 9999 && counter < 100000)
        {
            file.WriteLine("00" + counter.ToString());
        }
        else if (counter > 99999 && counter < 1000000)
        {
            file.WriteLine("0" + counter.ToString());
        }
        else if (counter > 999999 && counter < 10000000)
        {
            using (System.IO.StreamWriter file2 = new System.IO.StreamWriter(@"E:\numbers" + fileparam + ".txt"))
            {
                file.WriteLine(counter.ToString());
            }
        }
        if (counter % 50000 == 0)
        {
            fileparam++;
        }
    }

and all the files after numbers0.txt were empty.

Answer 1

You can try this:

var counter = 0;
var fileParam = 0;
StreamWriter sw = new StreamWriter(string.Format("C://archive/Numbers/numbers{0}.txt", fileParam));

while (counter < 10000000)
{
    sw.WriteLine(counter.ToString("D7"));
    if ((counter + 1) % 50000 == 0)
    {
        fileParam++;
        sw.Flush();
        sw.Close();
        sw = new StreamWriter(string.Format("C://archive/Numbers/numbers{0}.txt", fileParam));
    }
    counter++;
}

sw.Flush();
sw.Close();