Develop Reference

C# using streamwriter and streamreader at the same time to change line

so i searched a lot about how to change specific line in file, so i found the code which deletes line. I managed to edit the code and it changes exact line, but when i want to change other line after, previous word resets, and I dont know why.
This is the code which i found:
using (StreamReader reader = new StreamReader("C:\\input")) {
using (StreamWriter writer = new StreamWriter("C:\\output")) {
while ((line = reader.ReadLine()) != null) {
if (String.Compare(line, line_to_delete) == 0)
continue;
writer.WriteLine(line);
}
}
}
This is my edited code:
public void ChangeLineInFile(string file, string file2, string linetochange, string changedline) {
string line = null;
using (StreamReader reader = new StreamReader(file)) {
using (StreamWriter writer = new StreamWriter(file2)) {
while ((line = reader.ReadLine()) != null) {
if (String.Equals(line, linetochange)) {
writer.WriteLine(string.Format("{0}", changedline));
} else {
writer.WriteLine(line);
}
}
}
}
File.Delete(file);
File.Move(file2, file);
File.Delete(file2);
}

seems to me that your code does the following
file1->editA->file2
then you run it again. Did you copy file2 back over file1 before you started or did you just do
file1->editB->file2
After the first pass file1 still has the original data in it. So when you finish the function you need to copy the output file over the input file.

As I just explained above in the comments.
You are probably including your source file, the file you want to change, in Visual Studio in your project.
When you run your code from Visual Studio it will copy that source file to the output directory even if there is already a file present from the last execution.
The original file in your Visual Studio Project is not altered, only the copy that is included with the build output.
With each execution you are starting with the original file you have included in the project, you are not continuing with the file you had changed as this file is overwritten.
That said there are ways that you can specify if you want to include files as output during a build or if they should overwrite an existing file or not. Click on the file in the solution explorer and go to the properties (F4 shortcut on the keyboard). Both the Build Action and the Copy to Output Directory have to be taken into account.

C# Drag and Drop attached file from outlook email

I want to use/read attached files from an outlook email into a WinForm solution.
Ex: the email has a TXT file attached; I want to perform a Drag&Drog of the TXT file into the WinForm and read the TXT at the same time.

This is an old question, but I'll provide another answer anyhow that doesn't involve using the Outlook objects.
This URL provides working code that is about 13 years old, but still seems to work, on how to handle the "FileGroupDescriptor" and "FileContents" data that Outlook passes to the DropDrop event. Just in case that link dies, here is the relevant code, copy/pasted directly:
DragEnter event:
private void Form1_DragEnter(object sender, System.Windows.Forms.DragEventArgs e)
{
// for this program, we allow a file to be dropped from Explorer
if (e.Data.GetDataPresent(DataFormats.FileDrop))
{ e.Effect = DragDropEffects.Copy;}
// or this tells us if it is an Outlook attachment drop
else if (e.Data.GetDataPresent("FileGroupDescriptor"))
{ e.Effect = DragDropEffects.Copy;}
// or none of the above
else
{ e.Effect = DragDropEffects.None;}
}
DragDrop event:
private void Form1_DragDrop(object sender, System.Windows.Forms.DragEventArgs e)
{
string [] fileNames = null;
try
{
if ( e.Data.GetDataPresent(DataFormats.FileDrop,false) == true)
{
fileNames = (string []) e.Data.GetData(DataFormats.FileDrop);
// handle each file passed as needed
foreach( string fileName in fileNames)
{
// do what you are going to do with each filename
}
}
else if (e.Data.GetDataPresent("FileGroupDescriptor"))
{
//
// the first step here is to get the filename
// of the attachment and
// build a full-path name so we can store it
// in the temporary folder
//
// set up to obtain the FileGroupDescriptor
// and extract the file name
Stream theStream = (Stream) e.Data.GetData("FileGroupDescriptor");
byte [] fileGroupDescriptor = new byte[512];
theStream.Read(fileGroupDescriptor,0,512);
// used to build the filename from the FileGroupDescriptor block
StringBuilder fileName = new StringBuilder("");
// this trick gets the filename of the passed attached file
for(int i=76; fileGroupDescriptor[i]!=0; i++)
{ fileName.Append(Convert.ToChar(fileGroupDescriptor[i]));}
theStream.Close();
string path = Path.GetTempPath();
// put the zip file into the temp directory
string theFile = path+fileName.ToString();
// create the full-path name
//
// Second step: we have the file name.
// Now we need to get the actual raw
// data for the attached file and copy it to disk so we work on it.
//
// get the actual raw file into memory
MemoryStream ms = (MemoryStream) e.Data.GetData(
"FileContents",true);
// allocate enough bytes to hold the raw data
byte [] fileBytes = new byte[ms.Length];
// set starting position at first byte and read in the raw data
ms.Position = 0;
ms.Read(fileBytes,0,(int)ms.Length);
// create a file and save the raw zip file to it
FileStream fs = new FileStream(theFile,FileMode.Create);
fs.Write(fileBytes,0,(int)fileBytes.Length);
fs.Close(); // close the file
FileInfo tempFile = new FileInfo(theFile);
// always good to make sure we actually created the file
if ( tempFile.Exists == true)
{
// for now, just delete what we created
tempFile.Delete();
}
else
{ Trace.WriteLine("File was not created!");}
}
}
catch (Exception ex)
{
Trace.WriteLine("Error in DragDrop function: " + ex.Message);
// don't use MessageBox here - Outlook or Explorer is waiting !
}
}
Note that this code doesn't Dispose of objects that it should, such as the MemoryStream and FileStream objects.

You can get the running Outlook instance by using the GetActiveObject method which allows to obtain a running instance of the specified object from the running object table (ROT). Then you can automate Outlook to get the currently selected or opened item from which an attachment might be dragged. See C# app automates Outlook (CSAutomateOutlook) for the sample code.

An unhandled exception of type 'System.OutOfMemoryException' occurred in mscorlib.dll in LINQ Search

Using this article from MSDN, I'm trying to search through files in a directory. The problem is, every time I execute the program, I get:
"An unhandled exception of type 'System.OutOfMemoryException' occurred in mscorlib.dll".
I have tried to some other options like StreamReader, but I can't get it to work. These files are HUGE. Some of them range in upwards to 1.5-2GB each and there could be 5 or more files per day.
This code fails:
private static string GetFileText(string name)
{
var fileContents = string.Empty;
// If the file has been deleted since we took
// the snapshot, ignore it and return the empty string.
if (File.Exists(name))
{
fileContents = File.ReadAllText(name);
}
return fileContents;
}
Any ideas what could be happening or how to make it read without memory errors?
Entire code (in case you don't want to open the MSDN article)
class QueryContents {
public static void Main()
{
// Modify this path as necessary.
string startFolder = #"c:\program files\Microsoft Visual Studio 9.0\";
// Take a snapshot of the file system.
System.IO.DirectoryInfo dir = new System.IO.DirectoryInfo(startFolder);
// This method assumes that the application has discovery permissions
// for all folders under the specified path.
IEnumerable<System.IO.FileInfo> fileList = dir.GetFiles("*.*", System.IO.SearchOption.AllDirectories);
string searchTerm = #"Visual Studio";
// Search the contents of each file.
// A regular expression created with the RegEx class
// could be used instead of the Contains method.
// queryMatchingFiles is an IEnumerable<string>.
var queryMatchingFiles =
from file in fileList
where file.Extension == ".htm"
let fileText = GetFileText(file.FullName)
where fileText.Contains(searchTerm)
select file.FullName;
// Execute the query.
Console.WriteLine("The term \"{0}\" was found in:", searchTerm);
foreach (string filename in queryMatchingFiles)
{
Console.WriteLine(filename);
}
// Keep the console window open in debug mode.
Console.WriteLine("Press any key to exit");
Console.ReadKey();
}
// Read the contents of the file.
static string GetFileText(string name)
{
string fileContents = String.Empty;
// If the file has been deleted since we took
// the snapshot, ignore it and return the empty string.
if (System.IO.File.Exists(name))
{
fileContents = System.IO.File.ReadAllText(name);
}
return fileContents;
}
}

The problem you're having is based on trying to load multiple gigabytes of text at the same time. If they're text files, you can stream them and just compare one line at a time.
var queryMatchingFiles =
from file in fileList
where file.Extension == ".htm"
let fileLines = File.ReadLines(file.FullName) // lazy IEnumerable<string>
where fileLines.Any(line => line.Contains(searchTerm))
select file.FullName;

I would suggest that you are getting an out of memory error because the way the query is written I believe that you will need to load the entire text of every file into memory and none of the objects can be released until the entire file set has been loaded. Could you not check for the search term in the GetFileText function and then just return a true or false?
If you did that the file text at least falls out of scope at the end of the function and the GC can recover the memory. It would actually be better to rewrite as a streaming function if you are dealing with large files/amounts then you could exit your reading early if you come across the search term and you wouldn't need the entire file in memory all the time.
Previous question on finding a term in an HTML file using a stream

how to loop , read and write the folders and subfolders files

I am having a problem writing the files in folders and subfolders .
For Example:- test is the main folder
1) C:\test\
and i want to read and write the subfolder files
2)C:\test\12-05-2011\12-05-2011.txt
3)C:\test\13-05-2011\13-05-2011.txt
4)C:\test\14-05-2011\14-05-2011.txt
My code is:
private void button1_Click(object sender, EventArgs e)
{
const string Path1 = #"C:\test";
DoOnSubfolders(Path1);
try
{
StreamReader reader1 = File.OpenText(Path1);
string str = reader1.ReadToEnd();
reader1.Close();
reader1.Dispose();
File.Delete(Path1);
string[] Strarray = str.Split(new char[] { Strings.ChrW(10) });
int abc = Strarray.Length - 2;
int xyz = 0;
while (xyz <= abc)
}
I am getting an error. The error is
Access to the path 'C:\test' is denied.
Can anyone say me what i need to change in this code?

At first you could flatten your recursive calls by calling DirectoryInfo.GetFiles(string, SearchOption) and setting the SearchOption to AllDirectories.
What's also a common mistake (but not clear from your question) is that a directory needs to be created, before you can create a file. Simply call Directory.CreateDirectory(). And put in the complete path (without filename) into it. It will automatically do nothing if the directory already exists and is also able to create the whole needed structure. So no checks or recursive calls are needed (maybe a try-catch if you don't have write access).
Update
So here is an example that reads in a file, does some conversion on each line and writes the result into a new file. If this works properly the original file will be replaced by the converted one.
private static void ConvertFiles(string pathToSearchRecursive, string searchPattern)
{
var dir = new DirectoryInfo(pathToSearchRecursive);
if (!dir.Exists)
{
throw new ArgumentException("Directory doesn't exists: " + dir.ToString());
}
if (String.IsNullOrEmpty(searchPattern))
{
throw new ArgumentNullException("searchPattern");
}
foreach (var file in dir.GetFiles(searchPattern, SearchOption.AllDirectories))
{
var tempFile = Path.GetTempFileName();
// Use the using statement to make sure file is closed at the end or on error.
using (var reader = file.OpenText())
using (var writer = new StreamWriter(tempFile))
{
string line;
while (null != (line = reader.ReadLine()))
{
var split = line.Split((char)10);
foreach (var item in split)
{
writer.WriteLine(item);
}
}
}
// Replace the original file be the converted one (if needed)
////File.Copy(tempFile, file.FullName, true);
}
}
In your case you could call this function
ConvertFiles(#"D:\test", "*.*")

To recursively walk the sub-folders, you need a recursive function ie. One that calls itself. here is an example that should be enough for you to work with:
static void Main(string[] args)
{
const string path = #"C:\temp\";
DoOnSubfolders(path);
}
private static void DoOnSubfolders(string rootPath)
{
DirectoryInfo d = new DirectoryInfo(rootPath);
FileInfo[] fis = d.GetFiles();
foreach (var fi in fis)
{
string str = File.ReadAllText(fi.FullName);
//do your stuff
}
DirectoryInfo[] ds = d.GetDirectories();
foreach (var info in ds)
{
DoOnSubfolders(info.FullName);
}
}

You need use class Directory info and FileInfo.
DirectoryInfo d = new DirectoryInfo("c:\\test");
FileInfo [] fis = d.GetFiles();
DirectoryInfo [] ds = d.GetDirectories();

Here's a quick one liner to write the contents of all text files in a given directory (and all subdirectories) to the console:
Directory.GetFiles(myDirectory,"*.txt*",SearchOption.AllDirectories)
.ToList()
.ForEach(a => Console.WriteLine(File.ReadAllText(a)));

This code:
const string Path1 = #"C:\test";
StreamReader reader1 = File.OpenText(Path1);
Says open "c:\test" as a text file... The error you're getting is:
Access to the path 'C:\test' is denied
You're getting the error because as you stated above, 'c:\test' is a folder. You can't open folders like they are text files, hence the error...
A basic (full depth search) for files with a .txt extension looks like this:
static void Main(string[] args) {
ProcessDir(#"c:\test");
}
static void ProcessDir(string currentPath) {
foreach (var file in Directory.GetFiles(currentPath, "*.txt")) {
// Process each file (replace this with your code / function call /
// change signature to allow a delegate to be passed in... etc
// StreamReader reader1 = File.OpenText(file); // etc
Console.WriteLine("File: {0}", file);
}
// recurse (may not be necessary), call each subfolder to see
// if there's more hiding below
foreach (var subFolder in Directory.GetDirectories(currentPath)) {
ProcessDir(subFolder);
}
}

Have a look at http://support.microsoft.com/kb/303974 for a start. The secret is Directory.GetDirectories in System.IO.

You have to configure (NTFS) security on the c:\Test folder.
Normally you would have the application run under non-admininstrator account so the account that is running the program should have access.
If you are running on Vista or Windows 7 with UAC, you might be an administrator but you will not be using the administrative (elevated) permissions by default.
EDIT
Look at these lines:
const string Path1 = #"C:\test";
DoOnSubfolders(Path1);
try
{
StreamReader reader1 = File.OpenText(Path1);
That last line is trying to read the FOLDER 'c:\test' as if it was a text file.
You can't do that. What are you trying to accomplish there?

How to replace a data from a file if already exists and write a new data

Hi all i write a code to write my last row of datagrid view to a file as follows
private void Save_Click(object sender, EventArgs e)
{
if (dataGridView1.Rows.Count > 0)
{
List<string> lstContent = new List<string>();
foreach (DataGridViewRow row in dataGridView1.Rows)
{
if ((string)row.Cells[0].Value == "FileControl")
{
lstContent.Add((string)row.Cells[1].Value);
string mydata = string.Join(",", lstContent.ToArray());
using (StreamWriter sw = new StreamWriter(Append.FileName, true))
{
sw.WriteLine();
sw.Write(mydata);
}
}
}
}
}
But if i click multiple times on save this is writing that line multiple times what i need is if already that line exists in the file i have to replace that line with new line. Any help please

Your StreamWriter is explicitly using the file with append = true. Change the second parameter of the constructor to false if you want to overwrite the file each time. Docs are here. Quote:
append
Type: System.Boolean
Determines
whether data is to be appended to the
file. If the file exists and append is
false, the file is overwritten. If the
file exists and append is true, the
data is appended to the file.
Otherwise, a new file is created.
Revised code:
using (StreamWriter sw = new StreamWriter(Append.FileName, false))
{
sw.WriteLine();
sw.Write(mydata);
}
Replacing a given line in your file rather than just overwriting the whole file is a lot more difficult - this code is not going to get it done. StreamWriter is not great for this, you need random access and the ability to replace one data segment (line) by a different data segment of different length, which is an expensive operation on disk.
You might want to keep the files in memory as a container of Strings and do your required line replacement within the container, then write out the file to disk using File.WriteAllLines - that's if the file is not too big.