We Keep Coding

Compare two csv files in C#

I want to compare two csv files and print the differences in a file. I currently use the code below to remove a row. Can I change this code so that it compares two csv files or is there a better way in c# to compare csv files?
List<string> lines = new List<string>();
using (StreamReader reader = new StreamReader(System.IO.File.OpenRead(path)))
{
string line;
while ((line = reader.ReadLine()) != null)
{
if (line.Contains(csvseperator))
{
string[] split = line.Split(Convert.ToChar(scheidingsteken));
if (split[selectedRow] == value)
{
}
else
{
line = string.Join(csvseperator, split);
lines.Add(line);
}
}
}
}
using (StreamWriter writer = new StreamWriter(path, false))
{
foreach (string line in lines)
writer.WriteLine(line);
}
}

Here is another way to find differences between CSV files, using Cinchoo ETL - an open source library
For the below sample CSV files
sample1.csv
id,name
1,Tom
2,Mark
3,Angie
sample2.csv
id,name
1,Tom
2,Mark
4,Lu
METHOD 1:
Using Cinchoo ETL, below code shows how to find differences between rows by all columns
var input1 = new ChoCSVReader("sample1.csv").WithFirstLineHeader().ToArray();
var input2 = new ChoCSVReader("sample2.csv").WithFirstLineHeader().ToArray();
using (var output = new ChoCSVWriter("sampleDiff.csv").WithFirstLineHeader())
{
output.Write(input1.OfType<ChoDynamicObject>().Except(input2.OfType<ChoDynamicObject>(), ChoDynamicObjectEqualityComparer.Default));
output.Write(input2.OfType<ChoDynamicObject>().Except(input1.OfType<ChoDynamicObject>(), ChoDynamicObjectEqualityComparer.Default));
}
sampleDiff.csv
id,name
3,Angie
4,Lu
Sample fiddle: https://dotnetfiddle.net/nwLeJ2
METHOD 2:
If you want to do the differences by id column,
var input1 = new ChoCSVReader("sample1.csv").WithFirstLineHeader().ToArray();
var input2 = new ChoCSVReader("sample2.csv").WithFirstLineHeader().ToArray();
using (var output = new ChoCSVWriter("sampleDiff.csv").WithFirstLineHeader())
{
output.Write(input1.OfType<ChoDynamicObject>().Except(input2.OfType<ChoDynamicObject>(), new ChoDynamicObjectEqualityComparer(new string[] { "id" })));
output.Write(input2.OfType<ChoDynamicObject>().Except(input1.OfType<ChoDynamicObject>(), new ChoDynamicObjectEqualityComparer(new string[] { "id" })));
}
Sample fiddle: https://dotnetfiddle.net/t6mmJW

If you only want to compare one column you can use this code:
List<string> lines = new List<string>();
List<string> lines2 = new List<string>();
try
{
StreamReader reader = new StreamReader(System.IO.File.OpenRead(pad));
StreamReader read = new StreamReader(System.IO.File.OpenRead(pad2));
string line;
string line2;
//With this you can change the cells you want to compair
int comp1 = 1;
int comp2 = 1;
while ((line = reader.ReadLine()) != null && (line2 = read.ReadLine()) != null)
{
string[] split = line.Split(Convert.ToChar(seperator));
string[] split2 = line2.Split(Convert.ToChar(seperator));
if (line.Contains(seperator) && line2.Contains(seperator))
{
if (split[comp1] != split2[comp2])
{
//It is not the same
}
else
{
//It is the same
}
}
}
reader.Dispose();
read.Dispose();
}
catch
{
}

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();
}
}
}

c# Remove rows from csv

I have two csv files. In the first file i have a list of users, and in the second file i have a list of duplicate users. Im trying to remove the rows in the first file that are equal to the second file.
Heres the code i have so far:
StreamWriter sw = new StreamWriter(path3);
StreamReader sr = new StreamReader(path2);
string[] lines = File.ReadAllLines(path);
foreach (string line in lines)
{
string user = sr.ReadLine();
if (line != user)
{
sw.WriteLine(line);
}
File 1 example:
Modify,ABAMA3C,Allpay - Free State - HO,09072701
Modify,ABCG327,Processing Centre,09085980
File 2 Example:
Modify,ABAA323,Group HR Credit Risk & Finance
Modify,ABAB959,Channel Sales & Service,09071036
Any suggestions?
Thanks.

All you'd have to do is change the following file paths in the code below and you will get a file back (file one) without the duplicate users from file 2. This code was written with the idea in mind that you want something that is easy to understand. Sure there are other more elegant solutions, but I wanted to make it as basic as possible for you:
(Paste this in the main method of your program)
string line;
StreamReader sr = new StreamReader(#"C:\Users\J\Desktop\texts\First.txt");
StreamReader sr2 = new StreamReader(#"C:\Users\J\Desktop\texts\Second.txt");
List<String> fileOne = new List<string>();
List<String> fileTwo = new List<string>();
while (sr.Peek() >= 0)
{
line = sr.ReadLine();
if(line != "")
{
fileOne.Add(line);
}
}
sr.Close();
while (sr2.Peek() >= 0)
{
line = sr2.ReadLine();
if (line != "")
{
fileTwo.Add(line);
}
}
sr2.Close();
var t = fileOne.Except(fileTwo);
StreamWriter sw = new StreamWriter(#"C:\Users\justin\Desktop\texts\First.txt");
foreach(var z in t)
{
sw.WriteLine(z);
}
sw.Flush();

If this is not homework, but a production thing, and you can install assemblies, you'll save 3 hours of your life if you swallow your pride and use a piece of the VB library:
There are many exceptions (CR/LF between commas=legal in quotes; different types of quotes; etc.) This will handle anything excel will export/import.
Sample code to load a 'Person' class pulled from a program I used it in:
Using Reader As New Microsoft.VisualBasic.FileIO.TextFieldParser(CSVPath)
Reader.TextFieldType = Microsoft.VisualBasic.FileIO.FieldType.Delimited
Reader.Delimiters = New String() {","}
Reader.TrimWhiteSpace = True
Reader.HasFieldsEnclosedInQuotes = True
While Not Reader.EndOfData
Try
Dim st2 As New List(Of String)
st2.addrange(Reader.ReadFields())
If iCount > 0 Then ' ignore first row = field names
Dim p As New Person
p.CSVLine = st2
p.FirstName = st2(1).Trim
If st2.Count > 2 Then
p.MiddleName = st2(2).Trim
Else
p.MiddleName = ""
End If
p.LastNameSuffix = st2(0).Trim
If st2.Count >= 5 Then
p.TestCase = st2(5).Trim
End If
If st2(3) > "" Then
p.AccountNumbersFromCase.Add(st2(3))
End If
While p.CSVLine.Count < 15
p.CSVLine.Add("")
End While
cases.Add(p)
End If
Catch ex As Microsoft.VisualBasic.FileIO.MalformedLineException
MsgBox("Line " & ex.Message & " is not valid and will be skipped.")
End Try
iCount += 1
End While
End Using

this to close the streams properly:
using(var sw = new StreamWriter(path3))
using(var sr = new StreamReader(path2))
{
string[] lines = File.ReadAllLines(path);
foreach (string line in lines)
{
string user = sr.ReadLine();
if (line != user)
{
sw.WriteLine(line);
}
}
}
for help on the real logic of removal or compare, answer the comment of El Ronnoco above...

You need to close the streams or utilize using clause
sw.Close();
using(StreamWriter sw = new StreamWriter(#"c:\test3.txt"))

You can use LINQ...
class Program
{
static void Main(string[] args)
{
var fullList = "TextFile1.txt".ReadAsLines();
var removeThese = "TextFile2.txt".ReadAsLines();
//Change this line if you need to change the filter results.
//Note: this assume you are wanting to remove results from the first
// list when the entire record matches. If you want to match on
// only part of the list you will need to split/parse the records
// and then filter your results.
var cleanedList = fullList.Except(removeThese);
cleanedList.WriteAsLinesTo("result.txt");
}
}
public static class Tools
{
public static IEnumerable<string> ReadAsLines(this string filename)
{
using (var reader = new StreamReader(filename))
while (!reader.EndOfStream)
yield return reader.ReadLine();
}
public static void WriteAsLinesTo(this IEnumerable<string> lines, string filename)
{
using (var writer = new StreamWriter(filename) { AutoFlush = true, })
foreach (var line in lines)
writer.WriteLine(line);
}
}

using(var sw = new StreamWriter(path3))
using(var sr = new StreamReader(path))
{
string []arrRemove = File.ReadAllLines(path2);
HashSet<string> listRemove = new HashSet<string>(arrRemove.Count);
foreach(string s in arrRemove)
{
string []sa = s.Split(',');
if( sa.Count < 2 ) continue;
listRemove.Add(sa[1].toUpperCase());
}
string line = sr.ReadLine();
while( line != null )
{
string []sa = line.Split(',');
if( sa.Count < 2 )
sw.WriteLine(line);
else if( !listRemove.contains(sa[1].toUpperCase()) )
sw.WriteLine(line);
line = sr.ReadLine();
}
}

Fastest way to find strings in a file

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;
}
}
}

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