Develop Reference

text file: Reading line by line C#

So, let's say i have a text file with 20 lines, with on each line different text.
i want to be able to have a string that has the first line in it, but when i do NextLine(); i want it to be the next line. I tried this but it doesn't seem to work:
string CurrentLine;
int LastLineNumber;
Void NextLine()
{
System.IO.StreamReader file = new System.IO.StreamReader("c:\\test.txt");
CurrentLine = file.ReadLine(LastLineNumber + 1);
LastLineNumber++;
}
How would i be able to do this?
Thanks in advance.

In general, it would be better if you could design this in a way to leave your file open, and not try to reopen the file each time.
If that is not practical, you'll need to call ReadLine multiple times:
string CurrentLine;
int LastLineNumber;
void NextLine()
{
// using will make sure the file is closed
using(System.IO.StreamReader file = new System.IO.StreamReader("c:\\test.txt"))
{
// Skip lines
for (int i=0;i<LastLineNumber;++i)
file.ReadLine();
// Store your line
CurrentLine = file.ReadLine();
LastLineNumber++;
}
}
Note that this can be simplified via File.ReadLines:
void NextLine()
{
var lines = File.ReadLines("C:\\test.txt");
CurrentLine = lines.Skip(LastLineNumber).First();
LastLineNumber++;
}

One simple call should do it:
var fileLines = System.IO.File.ReadAllLines(fileName);
You will want to validate the file exists and of course you still need to watch for blank lines or invalid values but that should give you the basics. To loop over the file you can use the following:
foreach (var singleLine in fileLines) {
// process "singleLine" here
}
One more note - you won't want to do this with large files since it processes everything in memory.

Well, if you really don't mind re-opening the file each time, you can use:
CurrentLine = File.ReadLines("c:\\test.txt").Skip(LastLineNumber).First();
LastLineNumber++;
However, I'd advise you to just read the whole thing in one go using File.ReadAllLines, or perhaps File.ReadLines(...).ToList().

The ReadLine method already reads the next line in the StreamReader, you don't need the counter, or your custom function for that matter. Just keep reading until you reach your 20 lines or until the file ends.

You can't pass a line number to ReadLine and expect it to find that particular line. If you look at the ReadLine documentation, you'll see it doesn't accept any parameters.
public override string ReadLine()
When working with files, you must treat them as streams of data. Every time you open the file, you start at the very first byte/character of the file.
var reader = new StreamReader("c:\\test.txt"); // Starts at byte/character 0
You have to keep the stream open if you want to read more lines.
using (var reader = new StreamReader("c:\\test.txt"))
{
string line1 = reader.ReadLine();
string line2 = reader.ReadLine();
string line3 = reader.ReadLine();
// etc..
}
If you really want to write a method NextLine, then you need to store the created StreamReader object somewhere and use that every time. Somewhat like this:
public class MyClass : IDisposable
{
StreamReader reader;
public MyClass(string path)
{
this.reader = new StreamReader(path);
}
public string NextLine()
{
return this.reader.ReadLine();
}
public void Dispose()
{
reader.Dispose();
}
}
But I suggest you either loop through the stream:
using (var reader = new StreamReader("c:\\test.txt"))
{
while (some_condition)
{
string line = reader.ReadLine();
// Do something
}
}
Or get all the lines at once using the File class ReadAllLines method:
string[] lines = System.IO.File.ReadAllLines("c:\\test.txt");
for (int i = 0; i < lines.Length; i++)
{
string line = lines[i];
// Do something
}

Reading contents from several files and writing to one file

In my application there is a situation like this.Before creating a file, my application search for files in a directory under a particular filename. If any file/files found, then it should read each files contents and write these contents(of each file) to a new file. I have googled many and tried some like this:
string temp_file_format = "ScriptLog_" + DateTime.Now.ToString("dd_MM_yyyy_HH");
string[] files = Directory.GetFiles(path,temp_file_format);
foreach (FileAccess finfo in files)
{
string text = File.ReadAllText(finfo);
}
and
System.IO.DirectoryInfo dir = new DirectoryInfo(path);
System.IO.FileInfo[] files = dir.GetFiles(temp_file_format);
foreach (FileInfo finfo in files)
{
finfo.OpenRead();
}
But all these failed..Can anyone show me an alternative for this?
Is there anything wrong in my temp_file_format string?
It will be nice if I could prepend these contents to the new file. Else also, no worries..
any help would be really appreciated..

This is a compete working implementation that does all of that
without reading everything in memory at one time (which doesn't work for large files)
without keeping any files open for more than the required time
using System.IO;
using System.Linq;
public static class Program {
public static void Main()
{
var all = Directory.GetFiles("/tmp", "*.cpp")
.SelectMany(File.ReadAllLines);
using (var w = new StreamWriter("/tmp/output.txt"))
foreach(var line in all)
w.WriteLine(line);
}
}
I tested it on mono 2.10, and it should work on any .NET 4.0+ (for File.ReadAllLines which is a lazy linewise enumerable)

Here's a short snippet that reads all the files and out puts them to the path outputPath
var lines = from file in Directory.GetFiles(path,temp_file_format)
from line in File.ReadAllLines(file)
select line;
File.WriteAllLines(outputPath, content);
The problem you are having with your code is not really related to reading files but simply trying to use an object as a type it's not. Directory.GetFiles returns an array of string and File.ReadXXX and File.OpenRead expects the path as a string. So you simply need to pass each of the strings returned as the path argument to the appropriate method. The above is one such example. Hope it helps both solve your problem and explain the actually issue with your code

try this:
foreach (FileInfo finfo in files)
{
try
{
using (StreamReader sr = new StreamReader("finfo "))
{
String line = sr.ReadToEnd();
Console.WriteLine(line);
}
}
catch (Exception e)
{
Console.WriteLine("The file could not be read:");
Console.WriteLine(e.Message);
}
}

using (var output = File.Create(outputPath))
{
foreach (var file in Directory.GetFiles(InputPath,temp_file_format))
{
using (var input = File.OpenRead(file))
{
input.CopyTo(output);
}
}
}

Read text file from C# Resources

I need to read a file from my resources and add it to a list.
my code:
private void Form1_Load(object sender, EventArgs e)
{
using (StreamReader r = new StreamReader(Assembly.GetExecutingAssembly().GetManifestResourceStream("myProg.myText.txt")))
{
//The Only Options Here Are BaseStream & CurrentEncoding
}
}
Ive searched for this and only have gotten answers like "Assembly.GetExecutingAssembly...." but my program doesnt have the option of Assembly.?

Try something like this :
string resource_data = Properties.Resources.test;
List<string> words = resource_data.Split(new[] {Environment.NewLine}, StringSplitOptions.RemoveEmptyEntries).ToList();
Where

You need to include using System.Reflection; in your header in order to get access to Assembly. This is only for when you mark a file as "Embedded Resource" in VS.
var filename = "MyFile.txt"
System.Reflection.Assembly.GetExecutingAssembly().GetManifestResourceStream("YourNameSpace." + filename));
As long as you include 'using System.Reflection;' you can access Assembly like this:
Assembly.GetExecutingAssembly().GetManifestResourceStream("YourNamespace." + filename);
Or if you don't need to vary filename just use:
Assembly.GetExecutingAssembly().GetManifestResourceStream("YourNamespace.MyFile.txt");
The full code should look like this:
using(var reader = new StreamReader(Assembly.GetExecutingAssembly().GetManifestResourceStream("myProg.m‌​yText.txt"))
{
string line;
while ((line = reader.ReadLine()) != null)
{
// Do some stuff here with your textfile
}
}

Just to follow on this, AppDeveloper solution is the way to go.
string resource_data = Properties.Resources.test;
string [] words = resource_data.Split(new[] {Environment.NewLine}, StringSplitOptions.RemoveEmptyEntries);
foreach(string lines in words){
.....
}

[TestCategory("THISISATEST")]
public void TestResourcesReacheability()
{
byte[] x = NAMESPACE.Properties.Resources.ExcelTestFile;
string fileTempLocation = Path.GetTempPath() + "temp.xls";
System.IO.File.WriteAllBytes(fileTempLocation, x);
File.Copy(fileTempLocation, "D:\\new.xls");
}
You get the resouce file as a byte array, so you can use the WriteAllBytes to create a new file. If you don't know where can you write the file (cause of permissions and access) you can use the Path.GetTempPath() to use the PC temporary folder to write the new file and then you can copy or work from there.

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 replace 2 files?

i have this code snippet
private List<string> FolderOne(string Folder)
{
string filena;
DirectoryInfo dir = new DirectoryInfo(Folder);
FileInfo[] files = dir.GetFiles("*.mp3", SearchOption.AllDirectories);
List<string> str = new List<string>();
foreach (FileInfo file in files)
{
str.Add(file.FullName);
filena = file.FullName;
filena.Replace("*.mp3", "*.jpg");
if (filena.Length > 0)
{
pictureBox1.Image = new System.Drawing.Bitmap(filena.ToString()); //I receive a error "Parameter is not valid."
}
}
return str;
}
My purpose was to make read the picture box the file.fullname ".mp3" in the same folder but end with ".jpg",infact i have 2 file in a folder the first one is a song "firstsong.mp3" and the second one a picture "firstsong.jpg" the difference between them is the final extension so i try to make read to picturebox the same filename but with extension ".*jpg" and i receive an error "Parameter is not valid." in the line code "pictureBox1.Image = new System.Drawing.Bitmap(filena.ToString());".
How i can work out that?
Thanks for your attention
Nice Regards

There are some other issues with your code. First off, you are storing all the mp3 file names, but only displaying the last image loaded.
As far as replacing the extension, use Path's method to do that:
string musicFile = "mysong.mp3";
string imageFile = Path.ChangeExtension(musicFile, "jpg");

Switch to:
filena = filena.Replace(".mp3", ".jpg");
if (filena.Length > 0)
{
pictureBox1.Image = new System.Drawing.Bitmap(filena);
}
The main problem is with filena.Replace("*.mp3", "*.jpg");
There are two issues in that line.
First, you're searching on "*.mp3" instead of just ".mp3". The individual filenames do not have the * character, and string.Replace doesn't use regular expressions, just string matching.
Second, strings in .NET are immutable. They cannot be changed once they're created. This means that you can't replace the value of a string in place - you always return a new string. So string.Replace(...) will return a new string.

I'd add to the previous suggestions by adding that you should check that the jpg exists by doing the following:
if (File.Exists(jpgFilePath)) {
pictureBox1.Image = new System.Drawing.Bitmap(jpgFilePath);
}