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How to delete the last character of a file with C#

Hello I'm beginner with C# and I want to delete the last character of my file to inject JSON objects to this file manually (I know that's not the best way to do that), so I can get the right format I tried with multiple ways like open the file, manipulating the string (deleting the last character) and when I try to replace the text in that same file I have errors like IOException: The process cannot access the file 'file path' because it is being used by another process or System.UnauthorizedAccessException : 'Access to the path 'C:\Users\ASUS\Desktop\Root' is denied.
I'll show you the code :
StoreLogs Log = new StoreLogs()
{
Id = ID,
DateTime = dateT,
TaskName = task,
SrcAddress = srcPath,
DstAddress = path,
FileSize = DirSize(new DirectoryInfo(srcPath)),
DelayTransfer = ts.Milliseconds,
};
// Record JSON data in the variable
string strResultJson = JsonConvert.SerializeObject(Log);
// Show the JSON Data
// Console.WriteLine(strResultJson);
// Write JSON Data in another file
string MyJSON = null;
string strPath = #"C:\Users\ASUS\Desktop\Backup\logs\log.json";
if (File.Exists(strPath))
{
//FileInfo table = new FileInfo(strPath);
//string strTable = table.OpenText().ReadToEnd();
//string erase = strTable.Remove(strTable.LastIndexOf(']'));
//Console.WriteLine(erase);
//StreamReader r1 = new StreamReader(strPath);
//string strTable = r1.OpenText().ReadToEnd();
//string erase = strTable.Remove(strTable.LastIndexOf(']'));
//r1.Close();
using (StreamReader sr = File.OpenText(strPath))
{
string table = sr.ReadToEnd();
string erase = table.Remove(table.LastIndexOf(']'));
sr.Close();
File.WriteAllText(strPath, erase);
}
//MyJSON = "," + strResultJson;
//File.AppendAllText(strPath, MyJSON + "]");
//Console.WriteLine("The file exists.");
}
else if (!File.Exists(strPath))
{
MyJSON = "[" + strResultJson + "]";
File.WriteAllText(strPath, MyJSON);
Console.WriteLine("The file doesn't exists.");
}
else
{
Console.WriteLine("Error");
}
// End
Console.WriteLine("JSON Object generated !");
Console.ReadLine();
And that's the result I want :
[{"Id":"8484","DateTime":"26 novembre 2019 02:33:35 ","TaskName":"dezuhduzhd","SrcAddress":"C:\\Users\\ASUS\\Desktop\\Root","DstAddress":"C:\\Users\\ASUS\\Desktop\\Backup","FileSize":7997832.0,"DelayTransfer":0.0},{"Id":"8484","DateTime":"26 novembre 2019 02:33:35 ","TaskName":"dezuhduzhd","SrcAddress":"C:\\Users\\ASUS\\Desktop\\Root","DstAddress":"C:\\Users\\ASUS\\Desktop\\Backup","FileSize":7997832.0,"DelayTransfer":0.0},{"Id":"8484","DateTime":"26 novembre 2019 02:33:35 ","TaskName":"dezuhduzhd","SrcAddress":"C:\\Users\\ASUS\\Desktop\\Root","DstAddress":"C:\\Users\\ASUS\\Desktop\\Backup","FileSize":7997832.0,"DelayTransfer":0.0}]
Edit :
Thank you all for your advices
Solution:
FileStream fs = new FileStream(strPath, FileMode.Open, FileAccess.ReadWrite);
fs.SetLength(fs.Length - 1);
fs.Close();

In the code example you have posted you are opening a stream to read the file. A using block will dispose the stream after you exit the block. You are trying to write to the file, while the read stream is still accessing it (the read stream still exists). You've basically opened the file, you read from it, and are trying to write back to it while still holding it open. The reason this is a problem is that you are not using the stream to write. So your second, write, process is unable to access the file. I see you are closing the stream prior to write, but I'm willing to bet it's still holding the reference open.
I would try this method:
How to both read and write a file in C#

what it says is the access to the path (C:\Users\ASUS\Desktop\Root) denied for the user who is running the application. for ex: If you are running from Visual studio on user1 windows login then user1 should have appropriate rights to that root folder. If the code is running by itself (exe) then check the access for that user who is invoking that exe.

Based on the errors you posted seems that:
Maybe you're leaving some stream open pointing to the file you want to edit, use the 'using' statement to avoid this (see this link for more info)
You're trying to access a file when you don't have needed permissions (you aren't a system admin or file is read-only), try changing file ubication or setting it to be writeable (see this link for mor info about the UnauthorizedAccessException exception)
Hope this helps you!

C#: Unable to read file contents

I am trying to read the contents of a '.tmp' file provided as a command line argument in C#, but it either doesn't read the data or there might be some other issue:
PFB the code snippet in C# :
StreamReader inpFile2 = new StreamReader(args[1]);
string line;
while ((line = inpFile2.ReadLine()) != null) {
Console.WriteLine(line);
}
where args[1] is a.tmp file with the below contents:
Name: <<NAME>> (<<COURSE>>)
ID: <<ID>>
Total: <<TOTAL>>/100 Subtotal: <<SUBTOTAL>> Total deductions: <<LATEDEDUCTION>>
Time due: <<DUE>>
Submitted: <<SUBMITTED>>
Late minutes: <<MINUTESLATE>>
Late deduction: <<LATEDEDUCTION>>
Problem 1: <<P1>>/35
<<P1COMMENTS>>
Problem 2: <<P2>>/65
<<P2COMMENTS>>
It does not display anything.Can you point out what the problem is?I am new to C-sharp.

You can't just open a file with its name. You need its path too. Probably the current working directory.
Try changing
StreamReader inpFile2 = new StreamReader(args[1]);
To
var fileName = args[1];
var path = Path.Combine(Environment.CurrentDirectory, fileName);
StreamReader inpFile2 = new StreamReader(path);

Writing binary data to ftp location

How come this code writes an empty file at given location?
No error messages.
// upload file
WebRequest upload = WebRequest.Create(ftp + path + "/" + file);
upload.Method = WebRequestMethods.Ftp.UploadFile;
upload.Credentials = new NetworkCredential(username, password);
String filePath = HttpContext.Current.Server.MapPath("~/temp/" + file); // path to file to upload
Stream myReadStream = new FileStream(filePath, FileMode.Create); // stream that can read binary data
BinaryWriter myStreamWriter = new BinaryWriter(upload.GetRequestStream()); // writer that can write the binary data to the FTP server
while (myReadStream.ReadByte() != -1)
{
myStreamWriter.Write(myReadStream.ReadByte());
}
myStreamWriter.Close();
myReadStream.Close();
Removing the while loop creates a file 4byte big and corrupt so I guess I cant get in the while loop like this.

You should call upload.GetResponse() after myStreamWriter closed.
PS: In the while you write ONE time for every TWO times read, is it really you want?

How to determine if file completed downloading in SSH.NET

I am doing the following very basic task in SSH.NET/C# to download a file from a remote server to a local path:
ConnectionInfo c = new PasswordConnectionInfo(remoteIP, port, username, password);
var sftp = new SftpClient(c);
sftp.Connect();
using (var stream = new FileStream(destinationFile, FileMode.Create))
{
//download the file to our local path
sftp.DownloadFile(fileName, stream);
stream.Close();
}
sftp.Disconnect();
Now to determine if the file completely downloaded successfully, would that just be if the code block reached stream.Close()? Or is there a more concrete way to determine if everything was written okay?
EDIT: This post could be helpful to some if you want to see how many bytes have been downloaded. It also makes a primitive progress bar, which is convenient. I tested the code in the post and it does work.

Looking at the source code for SSH.NET, DownloadFile() is a blocking operation and will not return until the file is written fully.
Additionally, calling stream.Close() inside of the using block is not needed, as the object will be Disposed when exiting the block.

When I was working with SSH.NET a while back, for some reason I didn't know about or didn't like the fact that .DownloadFile had no return value. Either way, this was the route I took at the time.
StringBuilder sb = new StringBuilder();
ConnectionInfo c = new PasswordConnectionInfo(remoteIP, port, username, password);
var sftp = new SftpClient(c);
try
{
using (StreamReader reader = sftp.OpenText(fileName))
{
string line;
while ((line = reader.ReadLine()) != null)
{
sb.AppendLine(line);
}
}
File.WriteAllText(destinationFile, sb.ToString());
}
catch(Exception ex)
{
// procress exception
}

Saving File on Desktop by c#

I am using a web service that returns me some data. I am writing that data in a text file. my problem is that I am having a file already specified in the c# code, where I want to open a dialog box which ask user to save file in his desired location. Here I am posting code which I have used. Please help me in modifying my code. Actually after searching from internet, all are having different views and there is lot of changes in code required where as I do not want to change my code in extent. I am able to write the content in test file but how can I ask user to enter his desire location on computer?
StreamWriter file = new StreamWriter("D:\\test.txt");
HttpWebRequest webreq = (HttpWebRequest)WebRequest.Create(yahooURL);
// Get the response from the Internet resource.
HttpWebResponse webresp = (HttpWebResponse)webreq.GetResponse();
// Read the body of the response from the server.
StreamReader strm =
new StreamReader(webresp.GetResponseStream(), Encoding.ASCII);
string content = "";
for (int i = 0; i < symbols.Length; i++)
{
// Loop through each line from the stream,
// building the return XML Document string
if (symbols[i].Trim() == "")
continue;
content = strm.ReadLine().Replace("\"", "");
string[] contents = content.ToString().Split(',');
foreach (string dataToWrite in contents)
{
file.WriteLine(dataToWrite);
}
}
file.Close();

Try this
using (WebClient Client = new WebClient ())
{
Client.DownloadFile("http://www.abc.com/file/song/a.mpeg", "a.mpeg");
}