i have trouble with the following two functions. Both have a indentical basic scheme but first one work, second one causes an exception at marked line("File is used by another process").
// this works
public static void EncryptFile(string FileName)
{
string ToEncrypt = null;
using(StreamReader sr = new StreamReader(FileName))
{
ToEncrypt = sr.ReadToEnd();
}
using(StreamWriter sw = new StreamWriter(FileName, false))
{
string Encrypted = Encrypt(ToEncrypt, true);
sw.Write(Encrypted);
}
}
// this works not - see commented lin
public static void DecryptFile(string FileName)
{
string ToDecrypt = null;
using (StreamReader sr = new StreamReader(FileName))
{
ToDecrypt = sr.ReadToEnd();
}
// here comes the exception
using (StreamWriter sw = new StreamWriter(FileName, false))
{
string Decrypted = Decrypt(ToDecrypt, true);
sw.Write(Decrypted);
}
}
I have tried with an additional Close() after read and write, but this works not too.
I hope, somebody can help.
Thanks
Torsten
Is the function called from multiple threads? If yes you may want to declare a static object on class level and place a lock statement around the entire body of that method. Like this:
private static Object syncObject = new Object()
// this works not - see commented lin
public static void DecryptFile(string FileName)
{
lock(syncObject)
{
string ToDecrypt = null;
using (StreamReader sr = new StreamReader(FileName))
{
ToDecrypt = sr.ReadToEnd();
}
// here comes the exception
using (StreamWriter sw = new StreamWriter(FileName, false))
{
string Decrypted = Decrypt(ToDecrypt, true);
sw.Write(Decrypted);
}
}
}
Also could you, just for fun, comment the StreamReader statement and try to run the method again? If it still doesn't work, check if you've that file open in a texteditor or something alike by using ProcessExplorer or something similiar.
edit
could you comment the StreamReader part? So that it looks like this:
public static void DecryptFile(string FileName)
{
//string ToDecrypt = null;
//using (StreamReader sr = new StreamReader(FileName))
//{
// ToDecrypt = sr.ReadToEnd();
//}
// here comes the exception
using (StreamWriter sw = new StreamWriter(FileName, false))
{
string Decrypted = Decrypt(ToDecrypt, true);
sw.Write(Decrypted);
}
}
also could you try to open an exclusive FileStream on that file before the StreamReader and once after the StreamReader but before the StreamWriter? http://msdn.microsoft.com/de-de/library/tyhc0kft%28v=vs.110%29.aspx
Also could you try and use another file for that method?
Related
I've been trying to figure out what's my error here for a few minutes now. can someone help?
public void UpdateItemList(string word, string replacement)
{
StreamReader reader = new StreamReader("items.txt");
string input = reader.ReadToEnd();
using (StreamWriter writer = new StreamWriter("items.txt", true))
{
{
string output = input.Replace(word, replacement);
writer.Write(output);
}
writer.Close();
}
reader.Close();
}
I added reader.Close() and writer.Close() and gave different orientation, I'm not sure what I'm missing.
you should close StreamReader before opening streamWriter
public void UpdateItemList(string word, string replacement)
{
string input;
using (StreamReader reader = new StreamReader("items.txt"))
{
input = reader.ReadToEnd();
}
using (StreamWriter writer = new StreamWriter("items.txt", false))
{
string output = input.Replace(word, replacement);
writer.Write(output);
}
}
Currently, I was base on "Search and replace text in a document part (Open XML SDK)" on the Microsoft site. I've realized that the code got an issue after the file has downloaded to my drive.
So I opened that file and got a message
MEMORY STREAM IS NOT EXPANDABLE at sw.Write(docText);
How to fix that?
In GenerateDocxHelper class:
private readonly MemoryStream _mem;
private Dictionary<string, string> _dicData;
public GenerateDocxHelper(string path)
{
_mem = new MemoryStream(System.IO.File.ReadAllBytes(path));
_dicData = new Dictionary<string, string>();
}
public MemoryStream ReplaceTextInWord()
{
using (WordprocessingDocument wordDoc = WordprocessingDocument.Open(_mem, true))
{
string docText = null;
using (StreamReader sr = new StreamReader(wordDoc.MainDocumentPart.GetStream()))
{
docText = sr.ReadToEnd();
}
foreach (var data in _dicData)
{
docText = docText.Replace(data.Key, data.Value);
}
using (StreamWriter sw = new StreamWriter(wordDoc.MainDocumentPart.GetStream(FileMode.Create)))
{
sw.Write(docText);
}
}
_mem.Seek(0, SeekOrigin.Begin);
return _mem;
}
You should create the MemoryStream with capacity = 0 which means it is resizeable,
and then add the bytes you have read from the file.
var allBytes = File.ReadAllBytes(path);
//this makes _mem resizeable
_mem = new MemoryStream(0);
_mem.Write(allBytes, 0, allBytes.Length);
Check this answer
I'm trying to make betting program in C#, storing the user's data in a txt file. I have no problem reading the data from it. However, I can't manage to overwrite it.
From what I've tested, if I call the StreamWriter part alone the overwriting happens just fine. When I put the same code after the StreamReader part, the code will reach the Console.WriteLine("reached"); line and ignore everything after it (username is never written in the console). No error is detected and compilation won't stop either.
Here's the class code:
class Dinero
{
private List<string> data;
private string path = #"C:\Users\yy\Documents\Visual Studio 2015\Projects\ErikaBot\ErikaBot\img\bank_data.txt";
...
some other methods here
...
public void thing(string username, int money)
{
FileStream fs = new FileStream(path, FileMode.OpenOrCreate, FileAccess.ReadWrite, FileShare.None);
data = new List<string>();
using (StreamReader sr = new StreamReader(fs))
{
string a = sr.ReadLine();
for (int i = 0; a != null; i++)
{
if (a != username)
{
data.Add(a);
}
else i++;
a = sr.ReadLine();
}
}
string b = Convert.ToString(money);
Console.WriteLine("reached");
using (StreamWriter tw = new StreamWriter(fs))
{
Console.WriteLine(username);
if (data != null)
{
for (int i = 0; i < data.Count; i++)
{
tw.WriteLine(data.ElementAt(i));
}
}
string money2 = Convert.ToString(money);
tw.WriteLine(username);
tw.WriteLine(money2);
}
}
}
By disposing StreamReader you also dispose the FileStream.
Either repeat the filestream initialisation before the using statement for StreamWriter or put the latter in the using statement for StreamReader.
public bool ReadFile()
{
string fname = "text.txt";
FileStream fs = null;
fs = new FileStream(fname, FileMode.OpenOrCreate,FileAccess.Read);
StreamReader sr = new StreamReader(fs);
string res = sr.ReadToEnd();
if (res == "1")
return true;
else
return false;
}
public void WriteToFile()
{
string fname = "text.txt";
FileStream fs = null;
fs = new FileStream(fname, FileMode.Open,FileAccess.Write);
StreamWriter sw = new StreamWriter(fs);
sw.Write("1");
}
So it should work like if ReadFile returns false than i do WriteFile.
But when it reaches writefile, it throws IO expection:
The process cannot access the file ... because it is being used by another process
You aren't closing the file when you read it.
Put your FileStream and StreamReader objects in using statements:
using (var fs = new FileStream(fname, FileMode.OpenOrCreate,FileAccess.Read)) {
using (var sr = new StreamReader(fs)) {
//read file here
}
}
Make sure you do the same when you write to the file.
You need to dispose the StreamReader object in the ReadFile method. The StreamReader inherits from IDisposable and therfor you need to dispose the object.
Check this link for more info:StreamReader Class
I need to get my code to read if file doesnt exist create else append. Right now it is reading if it does exist create and append. Here is the code:
if (File.Exists(path))
{
using (StreamWriter sw = File.CreateText(path))
{
Would I do this?
if (! File.Exists(path))
{
using (StreamWriter sw = File.CreateText(path))
{
Edit:
string path = txtFilePath.Text;
if (!File.Exists(path))
{
using (StreamWriter sw = File.CreateText(path))
{
foreach (var line in employeeList.Items)
{
sw.WriteLine(((Employee)line).FirstName);
sw.WriteLine(((Employee)line).LastName);
sw.WriteLine(((Employee)line).JobTitle);
}
}
}
else
{
StreamWriter sw = File.AppendText(path);
foreach (var line in employeeList.Items)
{
sw.WriteLine(((Employee)line).FirstName);
sw.WriteLine(((Employee)line).LastName);
sw.WriteLine(((Employee)line).JobTitle);
}
sw.Close();
}
}
You can simply call
using (StreamWriter w = File.AppendText("log.txt"))
It will create the file if it doesn't exist and open the file for appending.
Edit:
This is sufficient:
string path = txtFilePath.Text;
using(StreamWriter sw = File.AppendText(path))
{
foreach (var line in employeeList.Items)
{
Employee e = (Employee)line; // unbox once
sw.WriteLine(e.FirstName);
sw.WriteLine(e.LastName);
sw.WriteLine(e.JobTitle);
}
}
But if you insist on checking first, you can do something like this, but I don't see the point.
string path = txtFilePath.Text;
using (StreamWriter sw = (File.Exists(path)) ? File.AppendText(path) : File.CreateText(path))
{
foreach (var line in employeeList.Items)
{
sw.WriteLine(((Employee)line).FirstName);
sw.WriteLine(((Employee)line).LastName);
sw.WriteLine(((Employee)line).JobTitle);
}
}
Also, one thing to point out with your code is that you're doing a lot of unnecessary unboxing. If you have to use a plain (non-generic) collection like ArrayList, then unbox the object once and use the reference.
However, I perfer to use List<> for my collections:
public class EmployeeList : List<Employee>
or:
using FileStream fileStream = File.Open(path, FileMode.Append);
using StreamWriter file = new StreamWriter(fileStream);
// ...
You don't even need to do the check manually, File.Open does it for you. Try:
using (StreamWriter sw = new StreamWriter(File.Open(path, System.IO.FileMode.Append)))
{
Ref: http://msdn.microsoft.com/en-us/library/system.io.filemode.aspx
2021
Just use File.AppendAllText, which creates the file if it does not exist:
File.AppendAllText("myFile.txt", "some text");
Yes, you need to negate File.Exists(path) if you want to check if the file doesn't exist.
This works as well for me
string path = TextFile + ".txt";
if (!File.Exists(HttpContext.Current.Server.MapPath(path)))
{
File.Create(HttpContext.Current.Server.MapPath(path)).Close();
}
using (StreamWriter w = File.AppendText(HttpContext.Current.Server.MapPath(path)))
{
w.WriteLine("{0}", "Hello World");
w.Flush();
w.Close();
}
This will enable appending to file using StreamWriter
using (StreamWriter stream = new StreamWriter("YourFilePath", true)) {...}
This is default mode, not append to file and create a new file.
using (StreamWriter stream = new StreamWriter("YourFilePath", false)){...}
or
using (StreamWriter stream = new StreamWriter("YourFilePath")){...}
Anyhow if you want to check if the file exists and then do other things,you can use
using (StreamWriter sw = (File.Exists(path)) ? File.AppendText(path) : File.CreateText(path))
{...}
For Example
string rootPath = Path.GetPathRoot(Environment.GetFolderPath(Environment.SpecialFolder.System));
rootPath += "MTN";
if (!(File.Exists(rootPath)))
{
File.CreateText(rootPath);
}
private List<Url> AddURLToFile(Urls urls, Url url)
{
string filePath = #"D:\test\file.json";
urls.UrlList.Add(url);
//if (!System.IO.File.Exists(filePath))
// using (System.IO.File.Delete(filePath));
System.IO.File.WriteAllText(filePath, JsonConvert.SerializeObject(urls.UrlList));
//using (StreamWriter sw = (System.IO.File.Exists(filePath)) ? System.IO.File.AppendText(filePath) : System.IO.File.CreateText(filePath))
//{
// sw.WriteLine(JsonConvert.SerializeObject(urls.UrlList));
//}
return urls.UrlList;
}
private List<Url> ReadURLToFile()
{
// string filePath = Path.Combine(Path.GetDirectoryName(Assembly.GetExecutingAssembly().Location), #"App_Data\file.json");
string filePath = #"D:\test\file.json";
List<Url> result = new List<Url>(); ;
if (!System.IO.File.Exists(filePath))
using (System.IO.File.CreateText(filePath)) ;
using (StreamReader file = new StreamReader(filePath))
{
result = JsonConvert.DeserializeObject<List<Url>>(file.ReadToEnd());
file.Close();
}
if (result == null)
result = new List<Url>();
return result;
}