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How can I extract xml file encoding using streamreader?

I needed to get the encoding type from the top of the xml file
<?xml version=“1.0” encoding=“utf-8”?>
but only the encoding="utf-8" is needed
the "utf-8" only without the quotation mark, how can I achieve this using streamreader?

You need utf-8 or encoding="utf-8" ? this block returns utf-8 as a result. If you need encoding="utf-8", you need to change.
using (var sr = new StreamReader(#"yourXmlFilePath"))
{
var settings = new XmlReaderSettings { ConformanceLevel = ConformanceLevel.Fragment };
using (var xmlReader = XmlReader.Create(sr, settings))
{
if (!xmlReader.Read()) throw new Exception("No line");
var result = xmlReader.GetAttribute("encoding"); //returns utf-8
}
}

Since it's xml, I would recommend XmlTextReader that provides fast, non-cached, forward-only access to XML data and read just top of the xml file since declaration is there. See following method:
string FindXmlEncoding(string path)
{
XmlTextReader reader = new XmlTextReader(path);
reader.Read();
if (reader.NodeType == XmlNodeType.XmlDeclaration)
{
while (reader.MoveToNextAttribute())
{
if (reader.Name == "encoding")
return reader.Value;
}
}
return null;
}

how can I achieve this using StreamReader?
Something like this:
using (StreamReader sr = new StreamReader("XmlFile.xml"))
{
string line = sr.ReadLine();
int closeQuoteIndex = line.LastIndexOf("\"") - 1;
int openingQuoteIndex = line.LastIndexOf("\"", closeQuoteIndex);
string encoding = line.Substring(openingQuoteIndex + 1, closeQuoteIndex - openingQuoteIndex);
}

const string ENCODING_TAG = "encoding"; //You are searching for this. Lets make it constant.
string line = streamReader.ReadLine(); //Use your reader here
int start = line.IndexOf(ENCODING_TAG);
start = line.IndexOf('"', start)+1; //Start of the value
int end = line.IndexOf('"', start); //End of the value
string encoding = line.Substring(start, end-start);
NOTE: This approach expects the encoding to be in the first line of an existing declaration. Which it does not need to be.

Replacing a certain word in a text file

I know this has been asked a few times, but I have seen a lot of regex etc., and I'm sure there is another way to do this with just a stream reader/writer. Below is my code. I'm trying to replace "tea" with the word "cabbage". Can somebody help? I believe I have the wrong syntax.
namespace Week_9_Exer_4
{
class TextImportEdit
{
public void EditorialControl()
{
string fileName;
string lineReadFromFile;
Console.WriteLine("");
// Ask for the name of the file to be read
Console.Write("Which file do you wish to read? ");
fileName = Console.ReadLine();
Console.WriteLine("");
// Open the file for reading
StreamReader fileReader = new StreamReader("C:\\Users\\Greg\\Desktop\\Programming Files\\story.txt");
// Read the lines from the file and display them
// until a null is returned (indicating end of file)
lineReadFromFile = fileReader.ReadLine();
Console.WriteLine("Please enter the word you wish to edit out: ");
string editWord = Console.ReadLine();
while (lineReadFromFile != null)
{
Console.WriteLine(lineReadFromFile);
lineReadFromFile = fileReader.ReadLine();
}
String text = File.ReadAllText("C:\\Users\\Greg\\Desktop\\Programming Files\\story.txt");
fileReader.Close();
StreamWriter fileWriter = new StreamWriter("C:\\Users\\Greg\\Desktop\\Programming Files\\story.txt", false);
string newText = text.Replace("tea", "cabbage");
fileWriter.WriteLine(newText);
fileWriter.Close();
}
}
}

If you don't care about memory usage:
string fileName = #"C:\Users\Greg\Desktop\Programming Files\story.txt";
File.WriteAllText(fileName, File.ReadAllText(fileName).Replace("tea", "cabbage"));
If you have a multi-line file that doesn't randomly split words at the end of the line, you could modify one line at a time in a more memory-friendly way:
// Open a stream for the source file
using (var sourceFile = File.OpenText(fileName))
{
// Create a temporary file path where we can write modify lines
string tempFile = Path.Combine(Path.GetDirectoryName(fileName), "story-temp.txt");
// Open a stream for the temporary file
using (var tempFileStream = new StreamWriter(tempFile))
{
string line;
// read lines while the file has them
while ((line = sourceFile.ReadLine()) != null)
{
// Do the word replacement
line = line.Replace("tea", "cabbage");
// Write the modified line to the new file
tempFileStream.WriteLine(line);
}
}
}
// Replace the original file with the temporary one
File.Replace("story-temp.txt", "story.txt", null);

In the end i used this : Hope it can help out others
public List<string> EditorialResponse(string fileName, string searchString, string replacementString)
{
List<string> list = new List<string>();
using (StreamReader reader = new StreamReader(fileName))
{
string line;
while ((line = reader.ReadLine()) != null)
{
line = line.Replace(searchString, replacementString);
list.Add(line);
Console.WriteLine(line);
}
reader.Close();
}
return list;
}
}
class Program
{
static void Main(string[] args)
{
TextImportEdit tie = new TextImportEdit();
List<string> ls = tie.EditorialResponse(#"C:\Users\Tom\Documents\Visual Studio 2013\story.txt", "tea", "cockrel");
StreamWriter writer = new StreamWriter(#"C:\Users\Tom\Documents\Visual Studio 2013\story12.txt");
foreach (string line in ls)
{
writer.WriteLine(line);
}
writer.Close();
}
}
}

Problems with text Encoding

I read txt file in ANSI or UTF-8 Encoding. Txt file consists of such lines:
79005213750:hello
79005213751:привет
79005213752:серега
Read it with such code:
TextReader readFile = new StreamReader(file_path, Encoding.Default);
foreach (string line in ReadLineFromFile(readFile))
{}
private static IEnumerable<string> ReadLineFromFile(TextReader fileReader)
{
using (fileReader)
{
string currentLine;
while ((currentLine = fileReader.ReadLine()) != null)
{
yield return currentLine;
}
}
}
and after all manipulations with lines I save them:
SaveFileDialog saveFile1 = new SaveFileDialog();
saveFile1.DefaultExt = "*.txt";
saveFile1.Filter = "TXT Files|*.txt";
saveFile1.FileName = "rus_number-pass";
if (saveFile1.ShowDialog() == System.Windows.Forms.DialogResult.OK && saveFile1.FileName.Length > 0)
{
using (System.IO.StreamWriter file = new System.IO.StreamWriter(saveFile1.FileName))
foreach (string line in digits_ru)
{
file.WriteLine(line);
}
}
In out I receive:
79005213750:hello
79005213751:привет
79005213752:серега
But expect :
79005213750:hello
79005213751:привет
79005213752:серега
Can u help me? I killed 2 days on this problem, but can't solve it=\

I believe you are using one encoding (Encoding.Default) for Read operations and another one (UTF8) for writing.
Use different overload of System.IO.StreamWriter constructor. E.g. this one
public StreamWriter(string path, bool append, Encoding encoding)
and as the encoding parameter pass the same default encoding you pass into the Reader.
TextReader readFile = new StreamReader(file_path, Encoding.Default);
I think that after you'll see the expected characters in the output file.
Btw. be aware that using Encoding.Default is not recommended.

You can specify the target encoding by using the codepage number:
var encoding = Encoding.GetEncoding(1251);
Which is russian, thats what you need I presume.

Data from newly created .text file is not readable to third party application

I have developed a windows application, which will read updated data from .jrn files(In an ATM Machine) and will be copy the text to a temporary text file "tempfile.txt".
There is another third party application called "POS Text Sender", which reads "tempfile.txt" and display the contents of it in a CCTV Camera.
The problem is that if I type directly something in the tempfile, the POS application will read it, but if my application writes text to "tempfile", I can see the same content as in the .jrn file in tempfile, but it is not reflected in the POS application when ever data is copied from newly generated file to tempfile.if restart the POS Text Sender after the first data copied to tempfile from newly generated file,POS Text sender will display the content til content from newly created file is written to tempfile
My application code is reading .jrn file using StreamReader and assigning it to a string variable and then writing it to a tempfile using StreamWriter. What is the difference between manually typing text on a file and .NET StreamWriter writing text to a file?
CODE:
DateTime LastChecked = DateTime.Now;
try
{
string[] files = System.IO.Directory.GetFiles(#"C:\Test", "*.jrn", System.IO.SearchOption.AllDirectories);
foreach (string file in files)
{
if (!fileList.Contains(file))
{
currentfilename = file;
fileList.Add(file);
copywarehouse(file);
//do_some_processing();
try
{
// Create an instance of StreamReader to read from a file.
// The using statement also closes the StreamReader.
using (StreamReader sr = new StreamReader(file))
{
currentcontent=sr.ReadToEnd();
// Read and display lines from the file until the end of
//// the file is reached.
//while ((currentcontent = sr.ReadLine()) != null)
//{
//}
sr.Close();
//sr.Dispose();
}
}
catch (Exception)
{
// Let the user know what went wrong.
}
}
}
//checking
try
{
using (StreamReader sr = new StreamReader(currentfilename))
{
string currentfilecontent = sr.ReadToEnd();
sr.Close();
//sr.Dispose();
if (currentfilecontent!=currentcontent)
{
if (currentfilecontent.Contains(currentcontent))
{
string originalcontent = currentfilecontent.Substring(currentcontent.Length);
System.IO.StreamWriter filenew = new System.IO.StreamWriter(#"C:\Test\tempfile.txt");
filenew.WriteLine(originalcontent);
filenew.Close();
currentcontent = currentfilecontent;
}
}
}
}
catch (Exception)
{
// Let the user know what went wrong.
}
copywarehouse method:
private void copywarehouse(string filename)
{
string sourcePath = #"C:\Test";
string targetPath = #"C:\Test";
try
{
string sourceFile = System.IO.Path.Combine(sourcePath, filename);
string destFile = System.IO.Path.Combine(targetPath, "tempfile.txt");
System.IO.File.Copy(sourceFile, destFile, true);
}
catch (Exception)
{
}
}

Can you check the following:
Is the generated file encoding same as the manually created file? (i.e. UTF-8/ANSI).
Are your constantly flushing the streamWriter's buffer? Or set the StreamWriter's AutoFlush property to true.
Is the StreamWriter opened with a WriteLock with no read allowed? In this case the other application may not be able to open your tempfile for read access.
EDIT:
Also, in the code you posted, you are comparing the tempFile data to current data, and if tempFile data is newer than current data, you are appending the temp file, which I think should be vice versa.
Main change:
using (StreamWriter filenew = new StreamWriter(fileDetail.TempFileName, true, Encoding.ASCII))
{
filenew.WriteLine(newContent);
}
To know the correct encoding, just create a new tempFile, write something in the editor and save it. Open the file in notepad and do a "save as". This will display the current encoding in the bottom. Set that encoding in .NET code.
If this does not work try (As recommended by shr):
using (StreamWriter filenew = new StreamWriter(fileDetail.TempFileName, true, Encoding.ASCII))
{
filenew.Write(newContent + "\r\n");
}
Long Version: (It may be a bit different than your code):
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
namespace ConsoleApplication1
{
class Program
{
static void Main(string[] args)
{
DateTime LastChecked = DateTime.Now;
IDictionary<string, FileDetails> fileDetails = new Dictionary<string, FileDetails>(StringComparer.OrdinalIgnoreCase);
IList<string> tempFileList = new List<string>();
try
{
string[] files = System.IO.Directory.GetFiles(#"C:\Test", "*.jrn", System.IO.SearchOption.AllDirectories);
foreach (string file in files)
{
string currentfilename = file;
string currentcontent = string.Empty;
if (!fileDetails.Keys.Contains(file))
{
fileDetails[file] = new FileDetails(copywarehouse(file));
//do_some_processing();
}
try
{
using (StreamReader sr = new StreamReader(file))
{
currentcontent = sr.ReadToEnd();
}
}
catch (Exception)
{
// Let the user know what went wrong.
}
fileDetails[file].AddContent(currentcontent);
}
//TODO: Check using the file modified time. Avoids unnecessary reading of file.
foreach (var fileDetail in fileDetails.Values)
{
//checking
try
{
string tempFileContent = string.Empty;
string currentcontent = fileDetail.GetContent();
using (StreamReader sr = new StreamReader(fileDetail.TempFileName))
{
tempFileContent = sr.ReadToEnd();
sr.Close();
}
if (!(0 == string.Compare(tempFileContent, currentcontent)))
{
if (currentcontent.Contains(tempFileContent))
{
string newContent = tempFileContent.Substring(currentcontent.Length);
using (StreamWriter filenew = new StreamWriter(fileDetail.TempFileName, true, Encoding.ASCII))
{
filenew.WriteLine(newContent);
}
}
}
}
catch (Exception)
{
// Let the user know what went wrong.
}
}
}
catch (Exception)
{
}
}
private static string copywarehouse(string filename)
{
string sourcePath = #"C:\Test";
string targetPath = #"C:\Test";
string sourceFile = System.IO.Path.Combine(sourcePath, filename);
string destFile = System.IO.Path.Combine(targetPath, filename+ "tempfile.txt");
try
{
System.IO.File.Copy(sourceFile, destFile, true);
}
catch (Exception)
{
}
return destFile;
}
internal class FileDetails
{
public string TempFileName { get; private set; }
private StringBuilder _content;
public FileDetails(string tempFileName)
{
TempFileName = tempFileName;
_content = new StringBuilder();
}
public void AddContent(string content)
{
_content.Append(content);
}
public string GetContent()
{
return _content.ToString();
}
}
}
}
EDIT 2:
Can you change the copywarehouse to this and see it the problem persists:
private void copywarehouse(string filename)
{
const string sourcePath = #"C:\Test";
const string targetPath = #"C:\Test";
try
{
string sourceFile = Path.Combine(sourcePath, filename);
string destFile = Path.Combine(targetPath, "tempfile.txt");
string currentcontent;
using (var sr = new StreamReader(sourceFile))
{
currentcontent = sr.ReadToEnd();
}
using (var wr = new StreamWriter(destFile, false, Encoding.ASCII))
{
wr.WriteLine(currentcontent);
}
}
catch (Exception)
{
}
}

Most likely this is a CR+LF issue.
The POS expects the file to have line endings with CR+LF (Carriage Return (0x0D) + New line (0x0A)) combination.
The filenew.WriteLine(originalcontent) appends only the new line character. When you type, I think, you editor must be creating the CR+LF combination for all line endings.
I suggest you try filenew.Write( originalcontent + "\r\n");

One difference is that your application does not write to tempfile.txt directly but to another file and then copies that file to tempfile.txt.

Delete specific line from a text file?

I need to delete an exact line from a text file but I cannot for the life of me workout how to go about doing this.
Any suggestions or examples would be greatly appreciated?
Related Questions
Efficient way to delete a line from a text file (C#)

If the line you want to delete is based on the content of the line:
string line = null;
string line_to_delete = "the line i want to delete";
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);
}
}
}
Or if it is based on line number:
string line = null;
int line_number = 0;
int line_to_delete = 12;
using (StreamReader reader = new StreamReader("C:\\input")) {
using (StreamWriter writer = new StreamWriter("C:\\output")) {
while ((line = reader.ReadLine()) != null) {
line_number++;
if (line_number == line_to_delete)
continue;
writer.WriteLine(line);
}
}
}

The best way to do this is to open the file in text mode, read each line with ReadLine(), and then write it to a new file with WriteLine(), skipping the one line you want to delete.
There is no generic delete-a-line-from-file function, as far as I know.

One way to do it if the file is not very big is to load all the lines into an array:
string[] lines = File.ReadAllLines("filename.txt");
string[] newLines = RemoveUnnecessaryLine(lines);
File.WriteAllLines("filename.txt", newLines);

Hope this simple and short code will help.
List linesList = File.ReadAllLines("myFile.txt").ToList();
linesList.RemoveAt(0);
File.WriteAllLines("myFile.txt"), linesList.ToArray());
OR use this
public void DeleteLinesFromFile(string strLineToDelete)
{
string strFilePath = "Provide the path of the text file";
string strSearchText = strLineToDelete;
string strOldText;
string n = "";
StreamReader sr = File.OpenText(strFilePath);
while ((strOldText = sr.ReadLine()) != null)
{
if (!strOldText.Contains(strSearchText))
{
n += strOldText + Environment.NewLine;
}
}
sr.Close();
File.WriteAllText(strFilePath, n);
}

You can actually use C# generics for this to make it real easy:
var file = new List<string>(System.IO.File.ReadAllLines("C:\\path"));
file.RemoveAt(12);
File.WriteAllLines("C:\\path", file.ToArray());

This can be done in three steps:
// 1. Read the content of the file
string[] readText = File.ReadAllLines(path);
// 2. Empty the file
File.WriteAllText(path, String.Empty);
// 3. Fill up again, but without the deleted line
using (StreamWriter writer = new StreamWriter(path))
{
foreach (string s in readText)
{
if (!s.Equals(lineToBeRemoved))
{
writer.WriteLine(s);
}
}
}

Read and remember each line
Identify the one you want to get rid
of
Forget that one
Write the rest back over the top of
the file

I cared about the file's original end line characters ("\n" or "\r\n") and wanted to maintain them in the output file (not overwrite them with what ever the current environment's char(s) are like the other answers appear to do). So I wrote my own method to read a line without removing the end line chars then used it in my DeleteLines method (I wanted the option to delete multiple lines, hence the use of a collection of line numbers to delete).
DeleteLines was implemented as a FileInfo extension and ReadLineKeepNewLineChars a StreamReader extension (but obviously you don't have to keep it that way).
public static class FileInfoExtensions
{
public static FileInfo DeleteLines(this FileInfo source, ICollection<int> lineNumbers, string targetFilePath)
{
var lineCount = 1;
using (var streamReader = new StreamReader(source.FullName))
{
using (var streamWriter = new StreamWriter(targetFilePath))
{
string line;
while ((line = streamReader.ReadLineKeepNewLineChars()) != null)
{
if (!lineNumbers.Contains(lineCount))
{
streamWriter.Write(line);
}
lineCount++;
}
}
}
return new FileInfo(targetFilePath);
}
}
public static class StreamReaderExtensions
{
private const char EndOfFile = '\uffff';
/// <summary>
/// Reads a line, similar to ReadLine method, but keeps any
/// new line characters (e.g. "\r\n" or "\n").
/// </summary>
public static string ReadLineKeepNewLineChars(this StreamReader source)
{
if (source == null)
throw new ArgumentNullException(nameof(source));
char ch = (char)source.Read();
if (ch == EndOfFile)
return null;
var sb = new StringBuilder();
while (ch != EndOfFile)
{
sb.Append(ch);
if (ch == '\n')
break;
ch = (char)source.Read();
}
return sb.ToString();
}
}

Are you on a Unix operating system?
You can do this with the "sed" stream editor. Read the man page for "sed"

What?
Use file open, seek position then stream erase line using null.
Gotch it? Simple,stream,no array that eat memory,fast.
This work on vb.. Example search line culture=id where culture are namevalue and id are value and we want to change it to culture=en
Fileopen(1, "text.ini")
dim line as string
dim currentpos as long
while true
line = lineinput(1)
dim namevalue() as string = split(line, "=")
if namevalue(0) = "line name value that i want to edit" then
currentpos = seek(1)
fileclose()
dim fs as filestream("test.ini", filemode.open)
dim sw as streamwriter(fs)
fs.seek(currentpos, seekorigin.begin)
sw.write(null)
sw.write(namevalue + "=" + newvalue)
sw.close()
fs.close()
exit while
end if
msgbox("org ternate jua bisa, no line found")
end while
that's all..use #d