Read / Write text file.

Question

Hello:

I would like to read in a text file and have it populate some objects in my program. Also I would like to change or delete some lines in the text file. Anyone know where I can find some sample code to help me do this? (Also I would like to add a new line or delete a line).

The following is what I would like to have in my test file:

User,Password,Sysytem,Database

Scott,Scott1212,HPV64,Devel

Scott,Scott1212,HPV64,Live

Bill,Bill3434,HPV64,Devel

Bill,Bill3434,HPV64,Live

Joe,Joe5656,VMW7,Devel

Joe,Joe5656,VMW7,Live

The objects I have on my form are:

textBoxUser_ID

textBoxPassword

comboBoxServer

comboBoxDatabase

Sam Hobbs · Answer

Actually all you have to do is to look at the previous replies in these forums. I know that I posted a complete working program for someone else sometime in the past couple of days. Okay look at Regex Troubles . The sample program in that should work for you also with slight modification. Note that in a Form application you can bind the DataTable to a DataGridView and then show the data in a grid relatively easily.

theLizard · Answer

So which is the best answer Sam ADO OLE JET ODBC Microsoft.VisualBasic.FileIO oh hang on now it is StreamReader / Writer in your 'article' all your code is it Sam one thing about you Sam you are consistent you don't know which is the best approach do you. I think just about everything has been suggested by now so what will be next? I can hardly wait for your next suggestion. Talk about adding layer upon layer upon layer reminds me of Sarah Lea makes great cakes but useless programs.

Sam Hobbs · Answer

Sometimes people post criticisms and then say that that should be the end of the conversation and that no further comments should be made. That is unreasonable; people can't have both. Either post criticisms or say that they don't intend to say anything more but don't do both including telling the other person to not comment further. I do agree there is no value in continuing this.

theLizard · Answer

I did not say that you insist on any particular method and nor do I I work on the basis of what is best for the situation and I considered the example I gave as the simplest solution for the question being asked as I understood it at that time from the many years of experience that I have. It seems that Giorgio is not entirely sure about anything and I do not criticize him for this as he is learning what my problem is with all of this dare I say it crap is that so many different methods were thrown at Giorgio along with misinformation that for a learner it would be confusing and daunting to deal with the different methodologies to achieve a simple task. The question was asked in different ways in different threads this also went to the heart of the matter where it appeared that Georgio did not know what he wanted and how to achieve it. Georgio goes of on a tangent learning things that are not necessary to learn if it is known that it is NOT going to be done that way at all. It is like a heart surgeon practicing on a healthy patient replacing a healty heart with a mechanical one just to see how the mechanical one would works. What a waste of time and effort this would be best utilized learning the methods and procedures of the tools you know you will be using. I have at all times in this thread and others relating to same maintained the one methodology and tyhat is using a stream reader to read in was or should have been a controled CSV file. Never once did I say learn THIS but you should know that THIS will be useless and that you should learn THAT but by the way you can do it THIS way if you used THIS or THAT but on the other hand you could youe STREAM READER / WRITER which I said in the first place. Now obviously Georgio likes to be bounced around a room like a rubber ball that is his choice and I will not deny him his rights to do that but you are offering tuition and you are bouncing him around. Sometimes it is best to leave crumbs for people to follow if Georgio is really keen to learn then he will pick up the crumbs and follow through with his own ideas and solutions which could ultimately be one of the methods you or I or anyone else suggested doing this may actually produce a really good programmer and this is the aim is it not! Now Sam I have had a number of businesses over the years one of those businesses was a software development house where we developed administrative applications dealing with educational institutions our clients were state and federal government as well as other very high profile international organizations I have been out of this business for some time now but it is still operational and still dealing with the organizations mentioned. The best solution for Georgio's needs is HIS choice not yours not mine whatever he is comfortable with is fine by me I would not be upset by the fact that he did not choose my method. Now let this be the end. One last piece of advice be consistent with your advice to others and help them learn let them find out about histories of how and what is happening in programming let them ask specific questions and simply point in the right direction don't spoon feed them.

Sam Hobbs · Answer

I don't insist that one way is best. You give the impression that you think flexibility is inferior and that there has to be one answer. I think that the answer to the question of what is best is that it depends on the requirements. Good software developers research requirements and then analyze them to determine what might be best. Sometimes the answer depends on personal experience and preferences. Businesses might choose the software that they want to use.

Sam Hobbs · Answer

See Simplistic Grid . It puts data into a DataGridView and gets the data out when the form is closed. It does not do much more than that but I hope it is enough to get you started.

Gustavo · Answer

Sam: YES... I would be intersted in that. Sounds a lot better that doing it with a txt file. I would like to see the code.

Sam Hobbs · Answer

Yes doing things such as editing the data is exactly why it is easier to use ADO. Using ADO .Net will do a lot for you. What you can do is to read the CSV file into a DataTable then bind a DataGridView to the DataTable. Or you can put the data into a DataGridView without a DataTable; I posted some code for that a few days ago. I think the question asked about how to put a two-dimensional array into a DataGridView. Are you interested in that?

Gustavo · Answer

Sam: I got this issue working well with the txt type sample code. However its a pain to edit the txt file. I have been surfing on how I can open an excel file. So this way I can change it easier outside of my application. I found 2 connectionStrings but neither one works. LOL

Sam Hobbs · Answer

The VisualBasic DLL has many useful classes that are not part of .Net but can be used by C#. Many experts would say it is wise to use the VisualBasic DLL. I am somewhat skeptical but I sure am not aware of any actual reason not to use it. In my opinion there should be a standard for CSV files that is supported by the CLI such as .Net and by languages such as C++. The VisualBasic DLL is the closest to that in Microsoft software.

Gustavo · Answer

Sam: With the using System.Data.Odbc seems I have the same issue. It does not work when I build with 'All CPU' but it works great with 'x86'. I went back and forth a few times to be sure. I will now try the: Microsoft.VisualBasic.FileIO

theLizard · Answer

Hi Sam. Having quotes is not a big deal all it means is that you could not use String.Split you would have to do the splitting yourself and that is NOT difficult. Dealing with the other things is really not that big a deal either. Before String.Split or anything else that you can use came along these little jobs had to be done by the programmer and you would be amazed at how much a person can learn about programming by doing these little tasks. String manipulation is a very important part of programming don't you think? Pulling apart strings and analyzing the components like html tags is probably how browsers work eg tells the browser that I need a window created ( in simple terms that is all a div actual is ). CSV's are no diferent.

Sam Hobbs · Answer

CSV files can have commas in the strings so they might have quotes around the text. Some CSV files can have quotes in the strings and dealing with that can be complicated. Some CSV files can have linefeeds in the strings and that can confuse some readers such as StreamReader. I don't know if linefeeds would confuse StreamReader specifically.

theLizard · Answer

Sorry Sam I must have missed something How much more difficult can CSV get? Comma Separated Values like abcd is a simple data structure is it not? How could you make CSV more complicated!!!!

Sam Hobbs · Answer

Yes for data as simple as the sample data provided in this question there is not need to get fancy. However if the data is more complicated CSV data then that will make the code more complicated. The CSV format was common in Basic and VB has some special support for CSV files. The VB TextFieldParser class can simplify things even for complex CSV data. using System; using Microsoft.VisualBasic.FileIO; namespace _79182 { class Program { static void Main(string[] args) { string Path = @C:\Users\Sam\Documents\Visual Studio 2008\Projects\C-SharpCorner\79182; string Filename = Data.txt; TextFieldParser Parser; try { Parser = new TextFieldParser(Path + '\' + Filename); Parser.TextFieldType = FieldType.Delimited; Parser.SetDelimiters(); } catch (Exception ex) { Console.WriteLine(Error: {0} ex.ToString()); return; } String[] Fields = null; int Line = 0; while (!Parser.EndOfData) { try { Fields = Parser.ReadFields(); } catch (Exception ex) { Console.WriteLine(Line {0} is not valid; error: {1} ++Line ex.Message); } if (Fields.Length != 4) { Console.WriteLine(Line does not have 4 fields:); Console.WriteLine(	{0} Fields); } else Console.WriteLine({0} | {1} | {2} | {3} Fields[0] Fields[1] Fields[2] Fields[3]); } } } }

theLizard · Answer

//a class to store values class lineElement { public string[] elements = new string[0]; } //your function to open and read the file.. lineElement[] e = new lineElement[0]; StreamReader sr = new StreamReader(dlgOpen.FileName); string l = ; while((l = sr.ReadLine()) != null) { //make sure you do some error checking like null strings etc.. Array.Resize(ref e e.Length +1); e[e.Length-1] = new lineElement(); Array.Resize(ref e[e.Length-1].elements getCount( l)); e[e.Length-1].elements = l.Split(new char[] {''}); } //a function to get how many delimiters in the line read from the file private int getCount(string delim string l) { int count = 0; while (l.IndexOf(delim) > 0) { l = l.Remove(l.IndexOf(delim) 1); count++; } return(count); } The above will allow you to read a file with mixed lengths of delimited values it will read this -- UserPasswordSysytemDatabase as well as this ScottScott1212HPV64 or this ScottScott1212 or this BillBill3434HPV64Devel UserPasswordSytemDatabase without any problem and with once you have the array you can do what you want add edit delete its not that hard to do... Ps. No Odbc No Jet No data adapters to bloat the system just simple string manipulation..

Gustavo · Answer

Sam: I looked around and it seems I do have the Msjet40.dll But I do get the error posted above for the code: da.Fill(dt); I would really like to use your solution... If I can get rid of this error.

Gustavo · Answer

Sam: I tried to test your sample and I can not get it to work. Seems from the information that I found by surfing is that the Jet.OLEDB is not supported on a x64 machine. I get the error: The 'Microsoft.Jet.OLEDB.4.0' provider is not registered on the local machine. Any suggestions?

Sam Hobbs · Answer

Yeah to be honest the subject of that post is Regex so you would not expect it to have the sample code that it does have. The important thing is that if your text file is in the format of a CSV then you can read it into a DataTable quite easily.

Gustavo · Answer

Sam: Thanks I will look at sample. I usually try to spent 1-2 hours searching for my solution untill I post. I tried to search but could not find anything that could help me. I must of not used the correct key words to find it. Thanks... will look at your sample.

Gustavo · Answer

I already looked at those. I was hoping that someone could point me to an actual sample with a running application so I can run it and look at how the code works.

Mahesh Chand · Answer

Here are two articles on how to read and write text files: TextReader and TextWriter in C# FileStream : Read or Write Data Streams You may also want to look into object serialization and deserialization. Search this site for these keywords.

Sam Hobbs · Answer

Also see Using CSV and Other Delimited Files in C# .