How can I make the file names to be raise by one each time a file is downloading?

Question

This is the code:

for (int i = 0; i < dateTime.Count; i++)
{
    string result = dateTime[i].ToString("yyyyMMddHHmm");
    link = "http://www.sattest.com + "&time=" + result + "&ir=" +
                       infraredorvisual;
    string filePath = Path.Combine(satimagesdir, "SatImage" + i + ".GIF");
    try
    {
        client1.DownloadFile(link, filePath);
    }
    catch (Exception e)
    {
        DannyGeneral.Logger.Write(e.ToString());
    }
}

In the first time when the program is running it's downloading 9 files. In dateTime List there are 9 items to download each time. The timer I'm using will download the files every 10 minutes.

The first I have 9 files on the hard disk. Then after 10 minutes I want that the next downloaded files will be named as SatImage10 then SatImage11...SatImage18

Next 10 minutes on the hard disk I want to see SatImage19 then SatImage20...SatImage27

How can I do it? The problem is that dateTime will contain always 9 files so the variable I will name the files all the time from SatImage0 to SatImage8.

Answer 1

Use a variable to mark where you left off:

private int last;

And increment it by the number of items each iteration, and use it to set the image name:

for (int i = 0; i < dateTime.Count; i++)
{
    ...
    string filePath = Path.Combine(satimagesdir, "SatImage" + (i + last) + ".GIF");
    ...
}
last += dateTime.Count;

If you close the application between downloads, you will need to iterate the files in the directory and extract the latest number from the file name.