i searched in stackoverflow and got one way but this method only let me to write word by word in the console. My goal is to get the end of my file but get the complete result not char by char.
This code only show me char by char the end of my file:
using (var reader = new StreamReader("file.dll")
{
if (reader.BaseStream.Length > 1024)
{
reader.BaseStream.Seek(-1024, SeekOrigin.End);
}
string line;
while ((line = reader.ReadLine()) != null)
{
Console.WriteLine(line);
Console.ReadKey();
}
}
I was trying to get something like this, it's c++ but i was trying to get the same result in c#.
QFile *archivo;
archivo = new QFile();
archivo->setFileName("file.dll");
archivo->open(QFile::ReadOnly);
archivo->seek(archivo->size() - 1024);
trama = archivo->read(1024);
It's possible to get the complete result of the end of my file in c#?
If the file is line-delimited text file, you can use ReadAllLines.
string[] lines = System.IO.File.ReadAllLines("file.txt");
If it's a binary file, you can use ReadAllBytes. Shocker, I know.
byte[] data = System.IO.File.ReadAllBytes("file.dll");
if you want to be able to seek first (e.g. if you want only the last 1024 bytes of the file) you can use the stream's Read method. Again, crazy.
reader.BaseStream.Seek(-1024, SeekOrigin.End);
var chars = new char[1024];
reader.Read(chars, 0, 1024);
And before you ask, you can convert the characters to a string by passing them to the constructor:
char[] chars = new char[1024];
string s = new string(chars);
Console.WriteLine(s);
Not sure what it'll look like, since you're reading characters from a binary file, but good luck. My guess is you should be reading bytes instead though:
reader.BaseStream.Seek(-1024, SeekOrigin.End);
var bytes = new byte[1024];
reader.BaseStream.Read(bytes, 0, 1024);
(Notice you don't even need the StreamReader, since the FileStream (your base stream) exposes the Read method you need).
Related
so I'm trying to load a file into a richtextbox, but I'm having some problems. No matter what method I used, binaryreader, filestream, streamreader I always encountered a problem with loading a file into a richtextbox in chunks. (I can't use LoadFile as it doesn't let me specify encoding). It seems that if the buffer size is too small, smaller than 3MB, AppendText sometimes adds a few extra empty lines. The file itself doesn't lose any data, there are just a few extra lines appended to it. Here is the code I'm using:
richTextBox.Clear();
progressBar.Value = 0;
const int bufferSize = 1024 * 1024 * 3; //I've tried smaller buffers but they ALL seem to append a few extra lines (empty lines)
using (StreamReader streamReader = new StreamReader(path))
{
while (streamReader.Peek() != -1)
{
char[] buffer = new char[bufferSize];
await streamReader.ReadBlockAsync(buffer, 0, bufferSize);
richTextBox.AppendText(new string(buffer));
progressBar.Value = (int)(((double)streamReader.BaseStream.Position) / streamReader.BaseStream.Length * 100);
}
}
This code seems to work, but I'm paranoid that it might still append extra lines at times depending on the circumstances. Does anybody know why this could be occurring?
*Extra Questions
Is using StreamReader slower than FileStream or binaryreader?
Should I use readblock or read?
This is the simple way you can use; it gives same format as in file:
OpenFileDialog fil = new OpenFileDialog();
if (fil.ShowDialog()== DialogResult.OK)
{
richTextBox1.Clear();
richTextBox1.Text = File.ReadAllText(fil.FileName);
}
Ack. I am trying to open a specific entry in a zip file archive and store the contents in a string, instead of saving it to a file. I cannot use disk space for this per the client.
Here's what I have:
string scontents = "";
byte[] abbuffer = null;
MemoryStream oms = new MemoryStream();
try
{
//get the file contents
ozipentry.Open().CopyTo(oms);
int length = (int)oms.Length; // get file length
abbuffer = new byte[length]; // create buffer
int icount; // actual number of bytes read
int isum = 0; // total number of bytes read
// read until Read method returns 0 (end of the stream has been reached)
while ((icount = oms.Read(abbuffer, isum, length - isum)) > 0)
{
isum += icount; // sum is a buffer offset for next reading
}
scontents = BytesToString(abbuffer); <----abbuffer is filled with Ascii 0
}
finally
{
oms.Close();
}
The variable abbuffer is supposed to hold that contents of the stream, but all it holds is a bunch of ascii zeros, which I guess means it didn't read (or copy) the stream! But I do not get any error messages or anything. Can someone tell me how to get this working?
I've looked everywhere on stack and on the web, and no where does anyone answer this question specifically for ASP.NET 4.5 ZipArchive library. I cannot use any other library, so if you offer an answer in that, while it would be educational, won't help me at all in this instance. Thanks so much for any help!
One more thing. 'ozipentry' is of type ZipArchiveEntry and is an element in a ZipArchive Entries array. (ie ozipentry = oziparchive.Entries[i])
Oops. One more thing! The function 'BytesToString' is not included, because it is irrelevant. Before the function is called, the abbuffer array is already filled with 0's
Ok. Sorry for being so dense. I realized I was overthinking this. I changed to function to do this:
osr = new StreamReader(ozipentry.Open(), Encoding.Default);
scontents = osr.ReadToEnd();
And it worked fine! Didn't even have to worry about Encoding...
There are two programs involved. The first one has a string like "##########". The second one is a config tool to find "##########" and replace this string with user input from a textbox.
Now I have trouble in the replacing part. Here is the code.
//This is code from first program:
string myIP = "####################";
string myPort = "%%%%%%%%";
int port = Int32.Parse(myIP );
tcpClient.Connect(myIP , port);
//This is code from second program：
//Get bytes from textbox:
byte[] byte_IP = new byte[60];
byte_IP = System.Text.Encoding.ASCII.GetBytes(textBox1_ip.Text);
//Get all bytes in the first program:
byte[] buffer = File.ReadAllBytes(#"before.exe");
//Replace string with textbox input, 0x1c00 is where the "#" starts:
Buffer.BlockCopy( byte_IP, 0, buffer, 0x1c00, byte_IP.Length);
//Build a new exe:
File.WriteAllBytes(#"after.exe", buffer);
However, I get "127.0.0.1#.#.#.#.#.#." in the new exe. But I need "1.2.7...0...0...1........." to process as a valid host.
First I'd like to reiterate what has already been said in the comments: there are simpler ways to handle this stuff. That's what config files are for, or registry settings.
But if you absolutely must...
First, you have to match the encoding that the framework expects. Is the string stored as UTF8? UTF16? ASCII? Writing data in the wrong encoding will turn it into pure garbage, almost every time. Generally for strings in code like you're looking for you'll be wanting to use Encoding.UNICODE.
Next, you need some way to deal with strings of different lengths. The buffer you define needs to be large enough to contain the widest string you want to be able to set - 15 bytes for dotted numeric IPv4 addresses - but you have to allow for the minimum of 7 characters. Padding the remainder and removing that padding before using the value will probably suffice.
The minimum program I could think to use for testing this was:
class Program
{
static void Main(string[] args)
{
var addr = "###.###.###.###".TrimEnd();
Console.WriteLine("Address: [{0}]", addr);
}
}
Now in your patcher you will need to locate the starting position in the file and overwrite the bytes with the new string's bytes. Here's a Patch method, which calls a FindString method that you will have to write yourself:
static void PatchFile(string filename, string searchString, string replaceString)
{
// Open the file
using (var file = File.Open(filename, FileMode.Open, FileAccess.ReadWrite, FileShare.ReadWrite))
{
// Locate the search string in the file (needs to be implemented)
long pos = FindString(file, searchString);
if (pos < 0)
return;
// Pad and limit replacement string, then convert to bytes
string rep = string.Format("{0,-" + searchString.Length + "}", replaceString).Substring(0, searchString.Length);
byte[] replaceBytes = Encoding.Unicode.GetBytes(rep);
// Overwrite the located bytes with the replacement
file.Position = pos;
file.Write(replaceBytes, 0, replaceBytes.Length);
}
}
Hopefully it makes sense.
Suppose the following lines in text file to which i have to read
INFO 2014-03-31 00:26:57,829 332024549ms Service1 startmethod - FillPropertyColor end
INFO 2014-03-31 00:26:57,829 332024549ms Service1 getReports_Dataset - getReports_Dataset started
INFO 2014-03-31 00:26:57,829 332024549ms Service1 cheduledGeneration - SwitchScheduledGeneration start
INFO 2014-03-31 00:26:57,829 332024549ms Service1 cheduledGeneration - SwitchScheduledGeneration limitId, subscriptionId, limitPeriod, dtNextScheduledDate,shoplimittype0, 0, , 3/31/2014 12:26:57 AM,0
I use the FileStream method to read the text file because the text file size having size over 1 GB. I have to read the files into chunks like initially in first run of program this would read two lines i.e. up to "getReports_Dataset started of second line". In next run it should read from 3rd line. I did the code but unable to get desired output.Problem is that my code doesn't give the exact chunk from where i have to start read text in next run. And second problem is while reading text lines .. don't give a complete line..i.e. some part is missing in lines. Following code:
readPosition = getLastReadPosition();
using (FileStream fStream = new FileStream(logFilePath, FileMode.Open, FileAccess.Read, FileShare.ReadWrite))
using (System.IO.StreamReader rdr = new System.IO.StreamReader(fStream))
{
rdr.BaseStream.Seek(readPosition, SeekOrigin.Begin);
while (numCharCount > 0)
{
int numChars = rdr.ReadBlock(block, 0, block.Length);
string blockString = new string(block);
lines = blockString.Split(Convert.ToChar('\r'));
lines[0] = fragment + lines[0];
fragment = lines[lines.Length - 1];
foreach (string line in lines)
{
lstTextLog.Add(line);
if (lstTextLog.Contains(fragment))
{
lstTextLog.Remove(fragment);
}
numProcessedChar++;
}
numCharCount--;
}
SetLastPosition(numProcessedChar, logFilePath);
}
If you want to read a file line-by-line, do this:
foreach (string line in File.ReadLines("filename"))
{
// process line here
}
If you really must read a line and save the position, you need to save the last line number read, rather than the stream position. For example:
int lastLineRead = getLastLineRead();
string nextLine = File.ReadLines("filename").Skip(lastLineRead).FirstOrDefault();
if (nextLine != null)
{
lastLineRead++;
SetLastPosition(lastLineRead, logFilePath);
}
The reason you can't do it by saving the base stream position is because StreamReader reads a large buffer full of data from the base stream, which moves the file pointer forward by the buffer size. StreamReader then satisfies read requests from that buffer until it has to read the next buffer full. For example, say you open a StreamReader and ask for a single character. Assuming that it has a buffer size of 4 kilobytes, StreamReader does essentially this:
if (buffer is empty)
{
read buffer (4,096 bytes) from base stream
buffer_position = 0;
}
char c = buffer[buffer_position];
buffer_position++; // increment position for next read
return c;
Now, if you ask for the base stream's position, it's going to report that the position is at 4096, even though you've only read one character from the StreamReader.
I need to read the first line from a stream to determine file's encoding, and then recreate the stream with that Encoding
The following code does not work correctly:
var r = response.GetResponseStream();
var sr = new StreamReader(r);
string firstLine = sr.ReadLine();
string encoding = GetEncodingFromFirstLine(firstLine);
string text = new StreamReader(r, Encoding.GetEncoding(encoding)).ReadToEnd();
The text variable doesn't contain the whole text. For some reason the first line and several lines after it are skipped.
I tried everything: closing the StreamReader, resetting it, calling a separate GetResponseStream... but nothing worked.
I can't get the response stream again as I'm getting this file from the internet, and redownloading it again would be bad performance wise.
Update
Here's what GetEncodingFromFirstLine() looks like:
public static string GetEncodingFromFirstLine(string line)
{
int encodingIndex = line.IndexOf("encoding=");
if (encodingIndex == -1)
{
return "utf-8";
}
return line.Substring(encodingIndex + "encoding=".Length).Replace("\"", "").Replace("'", "").Replace("?", "").Replace(">", "");
}
...
// true
Assert.AreEqual("windows-1251", GetEncodingFromFirstLine(#"<?xml version=""1.0"" encoding=""windows-1251""?>"));
** Update 2 **
I'm working with XML files, and the text variable is parsed as XML:
var feedItems = XElement.Parse(text);
Well you're asking it to detect the encoding... and that requires it to read data. That's reading it from the underlying stream, and you're then creating another StreamReader around the same stream.
I suggest you:
Get the response stream
Retrieve all the data into a byte array (or MemoryStream)
Detect the encoding (which should be performed on bytes, not text - currently you're already assuming UTF-8 by creating a StreamReader)
Create a MemoryStream around the byte array, and a StreamReader around that
It's not clear what your GetEncodingFromFirstLine method does... or what this file really is. More information may make it easier to help you.
EDIT: If this is to load some XML, don't reinvent the wheel. Just give the stream to one of the existing XML-parsing classes, which will perform the appropriate detection for you.
You need to change the current position in the stream to the beginning.
r.Position = 0;
string text = new StreamReader(r, Encoding.GetEncoding(encoding)).ReadToEnd();
I found the answer to my question here:
How can I read an Http response stream twice in C#?
Stream responseStream = CopyAndClose(resp.GetResponseStream());
// Do something with the stream
responseStream.Position = 0;
// Do something with the stream again
private static Stream CopyAndClose(Stream inputStream)
{
const int readSize = 256;
byte[] buffer = new byte[readSize];
MemoryStream ms = new MemoryStream();
int count = inputStream.Read(buffer, 0, readSize);
while (count > 0)
{
ms.Write(buffer, 0, count);
count = inputStream.Read(buffer, 0, readSize);
}
ms.Position = 0;
inputStream.Close();
return ms;
}