How to declare a file size limit when I am writing a file

Question

I am fairly new to C# and would like to ask how can I set a certain file limit to a comma-separated file. The scenario that I would be using them is as follows.

1. Before I write the CSV output file, I need to check if there is an existing CSV file or not on a specific path/drive
2. While the method is running, how can I make it stop writing before it exceeds its file size limit (preferably 500 MB worth of file size of CSV)?

This is currently the code I am using:

if (!File.Exists(newFileName))
{
    File.WriteAllText(newFileName, clientheader);
    //File.WriteAllText(logFileName, logfileheader);
}
else
{
    File.AppendAllText(newFileName, clientheader);
    // File.AppendAllText(logFileName, logfileheader);
}

Answer 1

You can use a stream (FileStream) for writing the csv data and check the current size by checking the Position property of the stream. Let's suppose you have data in the allData array that you want to write to a csv file (for example Name, Age, etc), then it should work like this:

const int sizeLimitInBytes = 500*1024*1024;

using (var stream = new FileStream("data.csv", FileMode.Append))
using (var writer = new StreamWriter(stream))
{
    // if the file is newly created then write the csv column names in the first line
    if (stream.Position == 0) 
    {
       writer.WriteLine("Name, Age, Job, Address");
    }

    foreach (var currentData in allData)
    {
        if (stream.Position > sizeLimitInBytes)
        {
            break;
        }
        writer.WriteLine("..."); // write data seperated by commas
    }
}

Use FileMode.Append to write to the end of the file if it exists. Otherwise it will create one.

StreamWriter uses buffering (with a 4 kilobyte buffer size), so checking whether the limit was exceeded won't be completely accurate, but for a 500 MB limit it doesn't really matter.

If you prefer to write all contents once to the file then you can use a MemoryStream instead of a FileStream, and then use File.WriteAllBytes to dump the bytes of the stream to the file.

Answer 2

I had a similar problem, a file was created with only limited characters. I found the solution and I tried "using " keyword while creating the file. Now the file is created with the maximum size.

using(StreamWriter sw = new StreamWriter(fs))
{
    ArrayList chartList = GetChart(maintNode);    
    foreach (var line in chartList)
    {
        sw.WriteLine(line);
    }
}

From: StreamWriter limit in C# in text file