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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!

Create folder google cloud storage bucket .NET Client Library

I'm looking to at a way to create a folder inside a bucket using the following client library:
https://cloud.google.com/storage/docs/json_api/v1/json-api-dotnet-samples
I've looked at the following thread, and it appears I need to use the simple method upload.
Creating folder in bucket google cloud storage using php
I can't see any way of being able to specify a uploadtype, all requests appear to be uploadType=resumable.
Looking at the above post and a fiddler trace I need to use uploadType=media. Is there away to accomplish this?

It is a bit more straighforward to do this in the latest version of the API.
You still have to make sure that you check for the "/" as Salem has suggested.
public void AddFolder(string folder)
{
StorageClient storageClient = StorageClient.Create();
if (!FolderName.EndsWith("/"))
FolderName += "/";
var content = Encoding.UTF8.GetBytes("");
storageClient.UploadObject(bucketName, folder, "application/x-directory", new MemoryStream(content));
}

This worked for me! Don't know if it's the right way to do it, but there are not enough on this.
public void CreateDir(string FolderName)
{
if (!FolderName.EndsWith("/"))
FolderName += "/";
var uploadStream = new MemoryStream(Encoding.UTF8.GetBytes(""));
Storage.Objects.Insert(
bucket: BucketName,
stream: uploadStream,
contentType: "application/x-directory",
body: new Google.Apis.Storage.v1.Data.Object() { Name = FolderName}
).Upload();
}
EDIT: Just found out that you can directly upload the file to your destination objects, and if the directories/sub-directories don't exist the upload function will create them for you.

All you need to do is put the folder(s) you want before the file name
using (MemoryStream ms = new MemoryStream(System.Text.Encoding.ASCII.GetBytes(json)))
{
string fileName = $"/test/somefolder/{sourceId}_{DateTime.Now.ToString("yyyyMMddHHmmss")}.json";
await gcpClient.UploadObjectAsync(gcpBucketName, fileName, null, ms);
}

Create text file in a given folder

I am developing a windows 8 app using Microsoft visual studio 2013. I needed to store the user entered data in a text file. I have wrote the following code segment to create the file and its working. But the text file is created in C:\Users...... I want to create the text file in a given folder. How can I modify my code to create the file in a folder where I specify.
StorageFile sampleFile;
const string fileName = "Sample.txt";

This is how you can create a file in C temp folder
String folderPath = #"C:/temp";
FileStream fs = new FileStream(folderPath + "\\Samplee.txt",FileMode.OpenOrCreate, FileAccess.Write);

As told before, Universal apps are sandboxed which means you can't write a file in an arbitrary folder.
You should take a look at the File access sample on how to do it.
Also, you should take a look at the ApplicationData which gives you a lot of choices for saving user entered data. Is it temporary, do you want it to be synced, is it a setting? There sure is a property that suits your needs.
edit: from http://msdn.microsoft.com/en-us/library/windows/apps/windows.storage.applicationdata.localfolder.aspx this is what you should do
var applicationData = Windows.Storage.ApplicationData.current;
var localFolder = applicationData.localFolder;
// Write data to a file
function writeTimestamp() {
localFolder.createFileAsync("dataFile.txt", Windows.Storage.CreationCollisionOption.replaceExisting)
.then(function (sampleFile) {
var formatter = new Windows.Globalization.DateTimeFormatting.DateTimeFormatter("longtime");
var timestamp = formatter.format(new Date());
return Windows.Storage.FileIO.writeTextAsync(sampleFile, timestamp);
}).done(function () {
});
}

You need to set the directory where you want to save the file.
Try this
string dirctory = #"D:\Folder Name"; //This is the location where you want to save the file
if (!Directory.Exists(dirctory))
{
Directory.CreateDirectory(dirctory);
}
File.WriteAllText(Path.Combine(dirctory, "Sample.txt"), "Text you want to Insert");

Get file path from inputstream?

I am trying to get the last modified date from a file, but need its path? Could someone please show me how i can get the file path?
[HttpGet]
public string uploadfile(string token, string filenameP, DateTime modDate, HttpPostedFileBase file)
{
MemoryStream target = new MemoryStream();
file.InputStream.CopyTo(target);
byte[] data = target.ToArray();
//ModDate = File.GetLastWriteTimeUtc("Path");
}

You are creating a new file on the server when you upload. The last modified date will be "now" (the time the file is created). There is no way to snoop the user's machine to get this information (which is not part of the file itself). Can't be done with an HTTP form upload.
Now, some file types may contain metadata in the file which may have pertinent information. If you know the file type and it does contain such metadata then you can open the file and have a look.

You just don't. Most (if not all) browsers do not provide this information for security reasons in internet sceanrios.

You can read date by javascript (HTML5) and send it as hidden input field of form.
Something like
<script>
function handleFileSelect(evt) {
var files = evt.target.files; // FileList object
// files is a FileList of File objects. List some properties.
var output = [];
for (var i = 0, f; f = files[i]; i++) {
output.push(f.lastModifiedDate ? f.lastModifiedDate.toLocaleDateString() );
}
document.getElementById('list').innerHTML = '<ul>' + output.join('') + '</ul>';
}
document.getElementById('files').addEventListener('change', handleFileSelect, false);
</script>
http://www.html5rocks.com/en/tutorials/file/dndfiles/

How to find the extension of a file in C#?

In my web application (asp.net,c#) I am uploading video file in a page but I want to upload only flv videos. How can I restrict when I upload other extension videos?

Path.GetExtension
string myFilePath = #"C:\MyFile.txt";
string ext = Path.GetExtension(myFilePath);
// ext would be ".txt"

You may simply read the stream of a file
using (var target = new MemoryStream())
{
postedFile.InputStream.CopyTo(target);
var array = target.ToArray();
}
First 5/6 indexes will tell you the file type. In case of FLV its 70, 76, 86, 1, 5.
private static readonly byte[] FLV = { 70, 76, 86, 1, 5};
bool isAllowed = array.Take(5).SequenceEqual(FLV);
if isAllowed equals true then its FLV.
OR
Read the content of a file
var contentArray = target.GetBuffer();
var content = Encoding.ASCII.GetString(contentArray);
First two/three letters will tell you the file type.
In case of FLV its "FLV......"
content.StartsWith("FLV")

At the server you can check the MIME type, lookup flv mime type here or on google.
You should be checking that the mime type is
video/x-flv
If you were using a FileUpload in C# for instance, you could do
FileUpload.PostedFile.ContentType == "video/x-flv"

I'm not sure if this is what you want but:
Directory.GetFiles(#"c:\mydir", "*.flv");
Or:
Path.GetExtension(#"c:\test.flv")

In addition, if you have a FileInfo fi, you can simply do:
string ext = fi.Extension;
and it'll hold the extension of the file (note: it will include the ., so a result of the above could be: .jpg .txt, and so on....

string FileExtn = System.IO.Path.GetExtension(fpdDocument.PostedFile.FileName);
The above method works fine with the Firefox and IE: I am able to view all types of files like zip,txt,xls,xlsx,doc,docx,jpg,png.
But when I try to find the extension of file from Google Chrome, I fail.

EndsWith()
Found an alternate solution over at DotNetPerls that I liked better because it doesn't require you to specify a path. Here's an example where I populated an array with the help of a custom method
// This custom method takes a path
// and adds all files and folder names to the 'files' array
string[] files = Utilities.FileList("C:\", "");
// Then for each array item...
foreach (string f in files)
{
// Here is the important line I used to ommit .DLL files:
if (!f.EndsWith(".dll", StringComparison.Ordinal))
// then populated a listBox with the array contents
myListBox.Items.Add(f);
}

It is worth to mention how to remove the extension also in parallel with getting the extension:
var name = Path.GetFileNameWithoutExtension(fileFullName); // Get the name only
var extension = Path.GetExtension(fileFullName); // Get the extension only

You will not be able to restrict the file type that the user uploads at the client side[*]. You'll only be able to do this at the server side. If a user uploads an incorrect file you will only be able to recognise that once the file is uploaded uploaded. There is no reliable and safe way to stop a user uploading whatever file format they want.
[*] yes, you can do all kinds of clever stuff to detect the file extension before starting the upload, but don't rely on it. Someone will get around it and upload whatever they like sooner or later.

You can check .flv signature. You can download specification here:
http://www.adobe.com/devnet/flv/
See "The FLV header" chapter.

private string GetExtension(string attachment_name)
{
var index_point = attachment_name.IndexOf(".") + 1;
return attachment_name.Substring(index_point);
}

This solution also helps in cases of more than one extension like "Avishay.student.DB"
FileInfo FileInf = new FileInfo(filePath);
string strExtention = FileInf.Name.Replace(System.IO.Path.GetFileNameWithoutExtension(FileInf.Name), "");

Path.GetExtension(file.FileName)) will get you the file name
Im also sharing a test code if someone needs to test and ge the extention or name.
Forming a text file with name test.txt and checking its extention in xUnit.
[Fact]
public void WrongFileExtention_returnError()
{
//Arrange
string expectedExtention = ".csv";
var content = "Country,Quantity\nUnited Kingdom,1";
var fileName = "test.csv";
var stream = new MemoryStream();
var writer = new StreamWriter(stream);
writer.Write(content);
writer.Flush();
stream.Position = 0;
//Act
IFormFile file = new FormFile(stream, 0, stream.Length, "", fileName);
//Assert
Assert.Equal(expectedExtention, Path.GetExtension(file.FileName));
}
Return true as the expected and the filename extention is name.
Hope this helps someone :).

I know this is quite an old question but here's a nice article on getting the file extension as well as a few more values:
Get File Extension in C#
I Hope That Helps :-)!