I'm trying to remove lines that are in between two different lines. Currently, I have:
string s = "";
String path = #"C:\TextFile";
StreamWriter sw = new StreamWriter(path, true);
StreamReader sr = new StreamReader(path, true);
s = sr.ReadLine();
if (s=="#Start")
{
while (s != "#End")
{
sw.WriteLine(s);
//need something here to overwrite existing data with s not just add s
}
}
sr.Close();
sw.Close();
The content of my text file looks like this:
#Start
facebook.com
google.com
youtube.com
#End
I tried to follow Efficient way to delete a line from a text file however it deletes any file containing a certain character, whereas there are other lines outside of the range containing .com that I don't want to remove
I want to delete all the contents in between start and end so after the method runs the remains of the text file is
#Start
#End
You have two problems:
You're only reading the first line, and then you're using that one value everywhere. Clearly if s == "#Start", it can't also satisfy the condition s == "#End", etc.
Even if you were reading each line, you expect that after #End there will be no more data - you don't loop through the rest of the lines, you just stop writing. Based on your question, I think you want to write all lines from the file and only change those between #Start and #End.
-
Perhaps a constant loop as below would be better?:
string s;
bool inRewriteBlock = false;
while ((s = sr.ReadLine()) != null)
{
if (s == "#Start")
{
inRewriteBlock = true;
}
else if (s == "#End")
{
inRewriteBlock = false;
}
else if (inRewriteBlock)
{
sw.WriteLine(s);
//need something here to overwrite existing data with s not just add s
}
else
{
sw.WriteLine(s);
}
}
By default, the code will output every line it reads verbatim. However, if it reads #Start it will enter a special mode (inRewriteBlock == true) where you can rewrite those lines however you want. Once it reaches #End it will transition back into the default mode (inRewriteBlock == false).
You can simply do this: (This assumes file can be stored in memory)
string path = #"C:\\Users\\test\\Desktop\\Test.txt";
List<string> fileData = File.ReadAllLines(path).ToList();
// File.ReadAllLines(path).ToList().Select(y => y.Trim()).ToArray().ToList(); will remove all trailing/preceding spaces in data
int startsWith = fileData.IndexOf("#Start");
int endsWith = fileData.IndexOf("#End");
if(startsWith != -1 && endsWith != -1)
fileData.RemoveRange(startsWith+1, endsWith-1);
File.WriteAllLines("C:\\Test\\Test1.txt", fileData.ToArray());
It doesnt account for special scenarios like startsWith is at the end of the file with no endswith.
You should check and rewrite every thing between #Start and #End instead of file is start with "#Start" only.
You can try this:
//Read all text lines first
string[] readText = File.ReadAllLines(path);
//Open the text file to write
var oStream = new FileStream(path, FileMode.Truncate, FileAccess.Write, FileShare.Read);
StreamWriter sw = new System.IO.StreamWriter(oStream);
bool inRewriteBlock = false;
foreach (var s in readText)
{
if (s.Trim() == "#Start")
{
inRewriteBlock = true;
sw.WriteLine(s);
}
else if (s.Trim() == "#End")
{
inRewriteBlock = false;
sw.WriteLine(s);
}
else if (inRewriteBlock)
{
//REWRITE DATA HERE (IN THIS CASE IS DELETE LINE THEN DO NOTHING)
}
else
{
sw.WriteLine(s);
}
}
sw.Close();
Related
I am using this code so far - it writes the file but doesn't remove the line specified.. any help would be nice...
if (textBox1.Text == "")
{
MessageBox.Show("Please select a file");
}
else
{
string line = null;
StringBuilder sb = new StringBuilder();
string lineDelete = "hi";
// Read the file and display it line by line.
using (System.IO.StreamReader file = new System.IO.StreamReader(textBox1.Text)){
using (System.IO.StreamWriter writer = new System.IO.StreamWriter("C:\\test3.txt"))
{
while ((line = file.ReadLine()) != null)
{
if (String.Compare (line, lineDelete) == 0)
continue;
writer.WriteLine(line);
}
MessageBox.Show("Formatting Complete");
// Suspend the screen.
}
}
"It doesn't remove the line specified" is somewhat misleading, isn't it? You are writing lines from file1 to file2, lines which are "hi" will be omitted. So you are ignoring, not deleting those lines. Is that what you want? Also, note that C# is case sensitive and that there also might be special characters which you can't see directly like white-spaces.
So you could use Trim to remove white-spaces from the start and end of the line and you can use String.Equals to compare case-insensitive:
while ((line = file.ReadLine()) != null)
{
line = line.Trim();
if(line.Equals(lineDelete, StringComparison.CurrentCultureIgnoreCase));
continue;
else
writer.WriteLine(line);
}
I am in a fight with overwriting of a text file with some of changes using a console application. Here I am reading the file line by line. Can any one help me.
StreamReader sr = new StreamReader(#"C:\abc.txt");
string line;
line = sr.ReadLine();
while (line != null)
{
if (line.StartsWith("<"))
{
if (line.IndexOf('{') == 29)
{
string s = line;
int start = s.IndexOf("{");
int end = s.IndexOf("}");
string result = s.Substring(start+1, end - start - 1);
Guid g= Guid.NewGuid();
line = line.Replace(result, g.ToString());
File.WriteAllLines(#"C:\abc.txt", line );
}
}
Console.WriteLine(line);
line = sr.ReadLine();
}
//close the file
sr.Close();
Console.ReadLine();
Here I am getting the error file is already open by another process.
Please help me, anyone. Main task is to overwrite the same texfile with modifications
You need a single stream,
open it for both reading and writing.
FileStream fileStream = new FileStream(
#"c:\words.txt", FileMode.OpenOrCreate,
FileAccess.ReadWrite, FileShare.None);
now you can use fileStream.Read() and fileStream.Write() methods
please see this link for extended discussion
How to both read and write a file in C#
The problem is that you're trying to write to a file that is used by the StreamReader. You have to close it or - better - use the using-statement which disposes/closes it even on error.
using(StreamReader sr = new StreamReader(#"C:\abc.txt"))
{
// ...
}
File.WriteAllLines(...);
File.WriteAllLines also writes all lines to the file not only the currrent line, so it's pointless to do it in the loop.
Can i suggest you a different method to read the lines of a text-file? You can use File.ReadAllLines which reads all lines into a string[] or File.ReadLines which works similar to a StreamReader by reading all lines lazily.
Here's a version doing the same but using a ( more readable?) LINQ query:
var lines = File.ReadLines(#"C:\abc.txt")
.Where(l => l.StartsWith("<") && l.IndexOf('{') == 29)
.Select(l =>
{
int start = l.IndexOf("{");
int end = l.IndexOf("}", start);
string result = l.Substring(start + 1, end - start - 1);
Guid g = Guid.NewGuid();
return l.Replace(result, g.ToString());
}).ToList();
File.WriteAllLines(#"C:\abc.txt", lines);
Problem is that you have opened the file and reading from same file at the same time you are writing in that file. But what you should do is,
Read the changes from the file
Close the file
Write the contents back to file
So your code should be like
List<string> myAppendedList = new List<string>();
using (StreamReader sr = new StreamReader(#"C:\abc.txt"))
{
string line;
line = sr.ReadLine();
while (line != null)
{
if (line.StartsWith("<"))
{
if (line.IndexOf('{') == 29)
{
string s = line;
int start = s.IndexOf("{");
int end = s.IndexOf("}");
string result = s.Substring(start + 1, end - start - 1);
Guid g = Guid.NewGuid();
line = line.Replace(result, g.ToString());
myAppendedList.Add(line);
}
}
Console.WriteLine(line);
line = sr.ReadLine();
}
}
if(myAppendedList.Count > 0 )
File.WriteAllLines(#"C:\abc.txt", myAppendedList);
Im creating a text file and the last line is ""
private void lastRunDate()
{
String lastLine = readLastDate();
String[] date = lastLine.Split('/');
DateTime dt = new DateTime(Int32.Parse(date[2]), Int32.Parse(date[0]), Int32.Parse(date[1]));
DateTime currentDT = DateTime.Now;
argValue = 1;
if ((dt.Month == currentDT.Month) && (argValue == 0))
{
MessageBox.Show("This application has already been run this month");
this.Close();
}
}
private void AddRecordToFile()
{
DateTime now = DateTime.Now;
prepareToEmail();
string path = filepath;
bool dirtyData = true;
// This text is added only once to the file.
if (!File.Exists(path))
{
// Create a file to write to.
using (StreamWriter sw = File.CreateText(path))
{
sw.Write(now.ToShortDateString());
}
dirtyData = false;
}
if (dirtyData)
{
// This text is always added, making the file longer over time
// if it is not deleted.
using (StreamWriter sw = File.AppendText(path))
{
sw.Write(now.ToShortDateString());
}
}
}
private String readLastDate()
{
using (StreamReader sr = new StreamReader(filepath))
{
// Initialize to null so we are not stuck in loop forever in case there is nothing in the file to read
String line = null;
do
{
line = sr.ReadLine();
// Is this the end of the file?
if (line == null)
{
// Yes, so bail out of loop
return "01/01/1900"; // I had to put something
}
// Is the line empty?
if (line == String.Empty)
{
// Yes, so skip it
continue;
}
// Here you process the non-empty line
return line;
} while (true);
}
}
is what I am using to create the file (or append it)
now is a DateTime object
I used your (Karl) code to create a method called "readLastDate()"
I get the 1st date instead.
I'm probably being way to pragmatic and simple, but skip all the stream stuff and use File class directly like this...
string newLine = "";
if (!isFirstLine)
newLine = Environment.NewLine;
File.AppendAllText(
filePath,
string.Format("{0}{1}", newLine, DateTime.Now.ToString()));
You could use a sw.Write and PRE-pend a linefeed. Unfortunately that will give you an empty line at the start of the file.
Have you tried using the command .Trimend ('\n')?
http://msdn.microsoft.com/en-us/library/system.string.trimend.aspx
Do this:
sw.Write(now.ToShortDateString());
Here is the MSDN documentation for StreamWriter.WriteLine.
Here is the MSDN documentation for StreamWriter.Write.
UPDATE:
Keep using the WriteLine, but change the way you read your values in from the file:
using (StreamReader sr = new StreamReader(path))
{
// Initialize to null so we are not stuck in loop forever in case there is nothing in the file to read
String line = null;
do
{
line = sr.ReadLine();
// Is this the end of the file?
if (line == null)
{
// Yes, so bail out of loop
return;
}
// Is the line empty?
if (line == String.Empty)
{
// Yes, so skip it
continue;
}
// Here you process the non-empty line
} while (true);
}
Adding a record should be a simple matter of calling File.AppendAllText, as pointed out in another answer. Although I would recommend:
File.AppendAllText(filePath, DateTime.Now.ToString() + Environment.NewLine);
To read the last date from the file is also very easy:
string lastGoodLine = "01/01/1900";
using (StringReader sr = new StringReader(filePath))
{
while (!sr.EndOfStream)
{
string line = sr.ReadLine();
if (!string.IsNullOrEmpty(line))
lastGoodLine = line;
}
}
return lastGoodLine;
I have a log file that is not more than 10KB (File size can go up to 2 MB max) and I want to find if atleast one group of these strings occurs in the files. These strings will be on different lines like,
ACTION:.......
INPUT:...........
RESULT:..........
I need to know atleast if one group of above exists in the file. And I have do this about 100 times for a test (each time log is different, so I have reload and read the log), so I am looking for fastest and bets way to do this.
I looked up in the forums for finding the fastest way, but I dont think my file is too big for those silutions.
Thansk for looking.
I would read it line by line and check the conditions. Once you have seen a group you can quit. This way you don't need to read the whole file into memory. Like this:
public bool ContainsGroup(string file)
{
using (var reader = new StreamReader(file))
{
var hasAction = false;
var hasInput = false;
var hasResult = false;
while (!reader.EndOfStream)
{
var line = reader.ReadLine();
if (!hasAction)
{
if (line.StartsWith("ACTION:"))
hasAction = true;
}
else if (!hasInput)
{
if (line.StartsWith("INPUT:"))
hasInput = true;
}
else if (!hasResult)
{
if (line.StartsWith("RESULT:"))
hasResult = true;
}
if (hasAction && hasInput && hasResult)
return true;
}
return false;
}
}
This code checks if there is a line starting with ACTION then one with INPUT and then one with RESULT. If the order of those is not important then you can omit the if () else if () checks. In case the line does not start with the strings replace StartsWith with Contains.
Here's one possible way to do it:
StreamReader sr;
string fileContents;
string[] logFiles = Directory.GetFiles(#"C:\Logs");
foreach (string file in logFiles)
{
using (StreamReader sr = new StreamReader(file))
{
fileContents = sr.ReadAllText();
if (fileContents.Contains("ACTION:") || fileContents.Contains("INPUT:") || fileContents.Contains("RESULT:"))
{
// Do what you need to here
}
}
}
You may need to do some variation based on your exact implementation needs - for example, what if the word spans two lines, does the line need to start with the word, etc.
Added
Alternate line-by-line check:
StreamReader sr;
string[] lines;
string[] logFiles = Directory.GetFiles(#"C:\Logs");
foreach (string file in logFiles)
{
using (StreamReader sr = new StreamReader(file)
{
lines = sr.ReadAllLines();
foreach (string line in lines)
{
if (line.Contains("ACTION:") || line.Contains("INPUT:") || line.Contains("RESULT:"))
{
// Do what you need to here
}
}
}
}
Take a look at How to Read Text From a File. You might also want to take a look at the String.Contains() method.
Basically you will loop through all the files. For each file read line-by-line and see if any of the lines contains 1 of your special "Sections".
You don't have much of a choice with text files when it comes to efficiency. The easiest way would definitely be to loop through each line of data. When you grab a line in a string, split it on the spaces. Then match those words to your words until you find a match. Then do whatever you need.
I don't know how to do it in c# but in vb it would be something like...
Dim yourString as string
Dim words as string()
Do While objReader.Peek() <> -1
yourString = objReader.ReadLine()
words = yourString.split(" ")
For Each word in words()
If Myword = word Then
do stuff
End If
Next
Loop
Hope that helps
This code sample searches for strings in a large text file. The words are contained in a HashSet. It writes the found lines in a temp file.
if (File.Exists(#"temp.txt")) File.Delete(#"temp.txt");
String line;
String oldLine = "";
using (var fs = File.OpenRead(largeFileName))
using (var sr = new StreamReader(fs, Encoding.UTF8, true))
{
HashSet<String> hash = new HashSet<String>();
hash.Add("house");
using (var sw = new StreamWriter(#"temp.txt"))
{
while ((line = sr.ReadLine()) != null)
{
foreach (String str in hash)
{
if (oldLine.Contains(str))
{
sw.WriteLine(oldLine);
// write the next line as well (optional)
sw.WriteLine(line + "\r\n");
}
}
oldLine = line;
}
}
}
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