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Find and replace with lookup file

I want to find and replace text in a textfile with a lookup file.
Currently i use the following code to replace a single string:
System.IO.StreamReader objReader;
objReader = new System.IO.StreamReader(someTextFile);
string content = objReader.ReadToEnd();
objReader.Close();
content = content.Replace("Text1", "Replacetext1");
System.IO.StreamWriter objWriter;
objWriter = new System.IO.StreamWriter(someTextFile);
objWriter.Write(content);
objWriter.Close();
I want to use a csv file for lookup. The format of this file is:
Text1, Replacedtext1
Text2, Replacedtext2
Text3, Replacedtext3
etc...
Who can me give some tips?
Thanks

OK Here are some tips:
1) use
string [] allLines = System.IO.File.ReadAllLines("yourLookUpFilePathHere");
it will return all lines in a string array. The same you can do with your file in which you want to make the replacements. Now you can loop through the look up file.
2) At each position / line in the array you can use the method:
string [] partsOfLine = allLines[i].Split('hereYourSeparatorAsChar');
3) now if you have fiddled out the first word you can start a second loop to look for matches in the replacement file and there you can use the line from your code:
allLinesOfReplaceFile[i] = allLinesOfReplaceFile[i].Replace("Text1", "Replacetext1");
I hope you get the drift, if it is still unclear then drop me a comment

get a set of strings from a text file based on codes in c#

I have a list of codes inside a text file I need to get a set of strings starting from one code to another one.
For example, If I have following data (there could be much more data in between) then I need to get the strings between
BS001 till ESS01
BS001 Customer ID|1234|Site Address||||
SS04,Data LANDMARK HOUSE, LONDON, UNITED KINGDOM|||
ESS01 ||
Currently I was working to read the file and go by each line. But how to take the substring starting from a code to the end of the code as the end of the code can be in any line like 5 or 10.
using (StreamReader sr = File.OpenText(fileName))
{
string s = String.Empty;
while ((s = sr.ReadLine()) != null)
{
SearchStringInaLine(s); // Method to search for ESS01 in the line
}
}

Instead of reading line by line, you can already get the full file contents into your string by using
sr.ReadToEnd();
Then you could build a loop and use
int bs001 = s.IndexOf("BS001");
int es001 = s.IndexOf("ES001");
string finding = s.Substring(bs001 + 5, es001 - bs001 - 5);
plus the offsets of the prvious findings to get all matching text (including line breaks) between BS001 and ES001.

Alternative to File.AppendAllText for newline

I am trying to read characters from a file and then append them in another file after removing the comments (which are followed by semicolon).
sample data from parent file:
Name- Harly Brown ;Name is Harley Brown
Age- 20 ;Age is 20 years
Desired result:
Name- Harley Brown
Age- 20
I am trying the following code-
StreamReader infile = new StreamReader(floc + "G" + line + ".NC0");
while (infile.Peek() != -1)
{
letter = Convert.ToChar(infile.Read());
if (letter == ';')
{
infile.ReadLine();
}
else
{
System.IO.File.AppendAllText(path, Convert.ToString(letter));
}
}
But the output i am getting is-
Name- Harley Brown Age-20
Its because AppendAllText is not working for the newline. Is there any alternative?

Sure, why not use File.AppendAllLines. See documentation here.
Appends lines to a file, and then closes the file. If the specified file does not exist, this method creates a file, writes the specified lines to the file, and then closes the file.
It takes in any IEnumerable<string> and adds every line to the specified file. So it always adds the line on a new line.
Small example:
const string originalFile = #"D:\Temp\file.txt";
const string newFile = #"D:\Temp\newFile.txt";
// Retrieve all lines from the file.
string[] linesFromFile = File.ReadAllLines(originalFile);
List<string> linesToAppend = new List<string>();
foreach (string line in linesFromFile)
{
// 1. Split the line at the semicolon.
// 2. Take the first index, because the first part is your required result.
// 3. Trim the trailing and leading spaces.
string appendAbleLine = line.Split(';').FirstOrDefault().Trim();
// Add the line to the list of lines to append.
linesToAppend.Add(appendAbleLine);
}
// Append all lines to the file.
File.AppendAllLines(newFile, linesToAppend);
Output:
Name- Harley Brown
Age- 20
You could even change the foreach-loop into a LINQ-expression, if you prefer LINQ:
List<string> linesToAppend = linesFromFile.Select(line => line.Split(';').FirstOrDefault().Trim()).ToList();

Why use char by char comparison when .NET Framework is full of useful string manipulation functions?
Also, don't use a file write function multiple times when you can use it only one time, it's time and resources consuming!
StreamReader stream = new StreamReader("file1.txt");
string str = "";
while ((string line = infile.ReadLine()) != null) { // Get every line of the file.
line = line.Split(';')[0].Trim(); // Remove comment (right part of ;) and useless white characters.
str += line + "\n"; // Add it to our final file contents.
}
File.WriteAllText("file2.txt", str); // Write it to the new file.

You could do this with LINQ, System.File.ReadLines(string), and System.File.WriteAllLines(string, IEnumerable<string>). You could also use System.File.AppendAllLines(string, IEnumerable<string>) in a find-and-replace fashion if that was, in fact, the functionality you were going for. The difference, as the names suggest, is whether it writes everything out as a new file or if it just appends to an existing one.
System.IO.File.WriteAllLines(newPath, System.IO.File.ReadLines(oldPath).Select(c =>
{
int semicolon = c.IndexOf(';');
if (semicolon > -1)
return c.Remove(semicolon);
else
return c;
}));
In case you aren't super familiar with LINQ syntax, the idea here is to loop through each line in the file, and if it contains a semicolon (that is, IndexOf returns something that is over -1) we cut that off, and otherwise, we just return the string. Then we write all of those to the file. The StreamReader equivalent to this would be:
using (StreamReader reader = new StreamReader(oldPath))
using (StreamWriter writer = new StreamWriter(newPath))
{
string line;
while ((line = reader.ReadLine()) != null)
{
int semicolon = line.IndexOf(';');
if (semicolon > -1)
line = c.Remove(semicolon);
writer.WriteLine(line);
}
}
Although, of course, this would feed an extra empty line at the end and the LINQ version wouldn't (as far as I know, it occurs to me that I'm not one hundred percent sure on that, but if someone reading this does know I would appreciate a comment).
Another important thing to note, just looking at your original file, you might want to add in some Trim calls, since it looks like you can have spaces before your semicolons, and I don't imagine you want those copied through.

Assign line in text file to a string

I'm making a simple text adventure in C# and I was wondering if it was possible to read certain lines from a .txt file and assign them to a string.
I am aware of how to read all the text from a .txt file but how exactly would I assign the contents of certain lines to a string?

Have you considered the ReadAllLines method?
It returns an array of lines from which you can choose your desired line.
So for eg, if you wish to choose the 3rd line (Assuming you have 3 lines in the file):
string[] lines = File.ReadAllLines(path);
string myThirdLine= lines[2];

Probably the easiest (and cheapest in terms of memory consumption) is File.ReadLines:
String stringAtLine10 = File.ReadLines(path).ElementAtOrDefault(9);
Note that it is null if there are less than 10 lines in the file. See: ElementAtOrDefault.
It's just the concise version of a StreamReader and a counter variable which increases on every line.

As an advanced alternative: ReadLines plus some LINQ:
var lines = File.ReadLines(myFilePath).Where(MyCondition).ToArray();
where MyCondition:
bool MyCondition(string line)
{
if (line == "something")
{
return true;
}
return false;
}

In case you don't want to load all lines atonce
using(StreamReader reader=new StreamReader(path))
{
String line;
while((line=reader.ReadLine())!=null)//process temp
}

Here's a example how you can assign the lines to a string, you can't decide which line is which via fields, you have to select them yourself.
which is the line of the string you want to assign.
For example, you want line one, you define which as one and not zero, you want line eight, you define which with eight.
string getWord(int which)
{
string readed = "";
using (Systen.IO.StreamReader read = new System.IO.StreamReader("PATH HERE"))
{
readed = read.ReadToEnd();
}
string[] toReturn = readed.Split('\n');
return toReturn[which - 1];
}

Parsing a textfile in C# with skipping some contents

I'm trying to parse a text file that has a heading and the body. In the heading of this file, there are line number references to sections of the body. For example:
SECTION_A 256
SECTION_B 344
SECTION_C 556
This means, that SECTION_A starts in line 256.
What would be the best way to parse this heading into a dictionary and then when necessary read the sections.
Typical scenarios would be:
Parse the header and read only section SECTION_B
Parse the header and read fist paragraph of each section.
The data file is quite large and I definitely don't want to load all of it to the memory and then operate on it.
I'd appreciate your suggestions. My environment is VS 2008 and C# 3.5 SP1.

You can do this quite easily.
There are three parts to the problem.
1) How to find where a line in the file starts. The only way to do this is to read the lines from the file, keeping a list that records the start position in the file of that line. e.g
List lineMap = new List();
lineMap.Add(0); // Line 0 starts at location 0 in the data file (just a dummy entry)
lineMap.Add(0); // Line 1 starts at location 0 in the data file
using (StreamReader sr = new StreamReader("DataFile.txt"))
{
String line;
int lineNumber = 1;
while ((line = sr.ReadLine()) != null)
lineMap.Add(sr.BaseStream.Position);
}
2) Read and parse your index file into a dictionary.
Dictionary index = new Dictionary();
using (StreamReader sr = new StreamReader("IndexFile.txt"))
{
String line;
while ((line = sr.ReadLine()) != null)
{
string[] parts = line.Split(' '); // Break the line into the name & line number
index.Add(parts[0], Convert.ToInt32(parts[1]));
}
}
Then to find a line in your file, use:
int lineNumber = index["SECTION_B";]; // Convert section name into the line number
long offsetInDataFile = lineMap[lineNumber]; // Convert line number into file offset
Then open a new FileStream on DataFile.txt, Seek(offsetInDataFile, SeekOrigin.Begin) to move to the start of the line, and use a StreamReader (as above) to read line(s) from it.

Well, obviously you can store the name + line number into a dictionary, but that's not going to do you any good.
Well, sure, it will allow you to know which line to start reading from, but the problem is, where in the file is that line? The only way to know is to start from the beginning and start counting.
The best way would be to write a wrapper that decodes the text contents (if you have encoding issues) and can give you a line number to byte position type of mapping, then you could take that line number, 256, and look in a dictionary to know that line 256 starts at position 10000 in the file, and start reading from there.
Is this a one-off processing situation? If not, have you considered stuffing the entire file into a local database, like a SQLite database? That would allow you to have a direct mapping between line number and its contents. Of course, that file would be even bigger than your original file, and you'd need to copy data from the text file to the database, so there's some overhead either way.

Just read the file one line at a time and ignore the data until you get to the ones you need. You won't have any memory issues, but performance probably won't be great. You can do this easily in a background thread though.

Read the file until the end of the header, assuming you know where that is. Split the strings you've stored on whitespace, like so:
Dictionary<string, int> sectionIndex = new Dictionary<string, int>();
List<string> headers = new List<string>(); // fill these with readline
foreach(string header in headers) {
var s = header.Split(new[]{' '});
sectionIndex.Add(s[0], Int32.Parse(s[1]));
}
Find the dictionary entry you want, keep a count of the number of lines read in the file, and loop until you hit that line number, then read until you reach the next section's starting line. I don't know if you can guarantee the order of keys in the Dictionary, so you'd probably need the current and next section's names.
Be sure to do some error checking to make sure the section you're reading to isn't before the section you're reading from, and any other error cases you can think of.

You could read line by line until all the heading information is captured and stop (assuming all section pointers are in the heading). You would have the section and line numbers for use in retrieving the data at a later time.
string dataRow = "";
try
{
TextReader tr = new StreamReader("filename.txt");
while (true)
{
dataRow = tr.ReadLine();
if (dataRow.Substring(1, 8) != "SECTION_")
break;
else
//Parse line for section code and line number and log values
continue;
}
tr.Close();
}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
}