Reading a List from a File using C#

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5.00/5 (1 vote)

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Good Morning experts,

As shown in this image:
http://s2.postimage.org/5ed0wl5tl/issue.jpg[^]

I am trying to save the data from a list to a text file. I am successfully righting ti file, but i cannot read from the file as shown in the image. I would really apprieciate all the help and wishing you a Happy new year.

Thanks :)

Posted 30-Dec-12 22:19pm

Gilmore Sacco

Updated 30-Dec-12 22:21pm

v2

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L Viljoen · Accepted Answer · 2012-12-30T22:33:00

Solution 1

Hi the problem is you are checking only once if the tr.readline is null. in your text file after the last item I would believe there is a space
Mr Saliba.
causing it to attempt to read the next one.

Also tr readline takes you to the next line so what to do is the following

Loop through the items but keep track of the index 0 - 3 (1 to 4 if your prefer

C#

int index = 0;
string value;
while((value = tr.Readline()) != null){
if(index == 1){
 stList[counter].firstname = value;
} else if//. . . . all the cases

}

index++;

if(index == 4){
index = 1;
}

}

[Edit]Syntax errors fixed[/Edit]

Posted 30-Dec-12 22:33pm

L Viljoen

Updated 30-Dec-12 22:38pm

v2

Comments

Thomas Daniels 31-Dec-12 4:38am

Good solution, +5!

Gilmore Sacco 31-Dec-12 4:38am

hello sir and thx for your quick response. I did understand what are you saying, but the problem is i dont know how many profiles of students does the file contain.

prashant patil 4987 31-Dec-12 4:43am

5+.... owesome solution

L Viljoen 31-Dec-12 4:45am

Heres what you can do is , if you have 4 lines per student. then I suggest you can use the Readall lines command

string[] lines = System.IO.File.ReadAllLines("Filepath");
if(lines.count != 0){ //avoid zero devision error
int studentCount = lines.count /4
}

but I would recommadn instead of having diferent lines per block of info is creating comma delimited information

firstname, surname, telephone ect

so you have 1 student per line, then you can simply use a
Regex.Split(line, ",")
to split the information and read the text like that , much xleaner and less prone to error.

Gilmore Sacco 31-Dec-12 4:52am

thx chonal1171. is it possible to find an example or an article i can read about your solution please?

Gilmore Sacco 31-Dec-12 4:48am

hello again, i read the solution multiple times, i have an idea of what you are saying but still i cannot quite understand it. Can you please explain it again to me?

L Viljoen 31-Dec-12 7:58am

Ok lets say in your text file you have the following file in "c:\myfile.txt":
1, John Smith,054 654 1234
2, Jane Smith,054 654 1235
3, Andrew Smith, 054 654 1236

This is comma delimited data in the form: id, fullname, phone number

now you wish to break it down so in C# you go
string filename = @"C:\myfile.txt";
string[] fileLines = System.IO.File.ReadAllLines(filename);
foreach(string line in fileLines){
string[] dataBreakdown = System.Text.RegularExpressions.Regex.Split(line,","); //seperating the comma delimited data
Console.WriteLine("ID:"+dataBreakdown[0]+" Full Name: "+dataBreakdown[1] +" Tel: "+dataBreakdown[2];
}

Gilmore Sacco 31-Dec-12 9:40am

I tried this method and it worked great for the purpose you made it. My original purpose is a liitle different. I have iploaded a screenshot. If you can help me it would be fantastic, as i feel very close to finally make it.
http://s1.postimage.org/dfruddoi7/Problem.jpg Thank you very much :)

L Viljoen 2-Jan-13 0:14am

I looked at the error, can you please show me the format of your text file becuase something tells me its not comma dlimited or place a line

if(line.Length > 3){
string[] dataBreakdown = System.Text.RegularExpressions.Regex.Split(line,","); //seperating the comma delimited data Console.WriteLine("ID:"+dataBreakdown[0]+" Full Name: "+dataBreakdown[1] +" Tel: "+dataBreakdown[2];
}
after the foreach string

sariqkhan 31-Dec-12 8:12am

can you help me sir fox
http://www.codeproject.com/Questions/519171/showingplusonlyplustheplusfilteredpluscolumnplusin

OriginalGriff · Accepted Answer · 2012-12-30T22:40:00

Solution 2

When you read from a file by calling ReadLine, you take a line of text from the file, return it, and advance the pointer. So when you discard one of those lines each time you go round the loop by reading a line and checking if it is null, you are both getting out of step, and running out of file.
Suppose your file contains

Name1
Surname1
Address1
Preference1
Name2
Surname2
Address2
Preference2
Name3
Surname3
Address3
Preference3

The entry to your loop reads and discards "Name1", then puts "Surname1" into the Name field, "Address1" into teh Surname feild, "Preference1" into the Address field, and "Name2" into the Preference field.

Change the Loop condition:

C#

while (tr.Peek() >= 0)

Posted 30-Dec-12 22:40pm

OriginalGriff

Comments

Gilmore Sacco 31-Dec-12 4:44am

hello OriginalGriff,

I did try your suggestion but still, the the problem persists.

OriginalGriff 31-Dec-12 4:53am

Is there any chance that you are saving data which may contain newlines? For example, addresses often do - if any single address contains a newline, it will throw out your whole system.

Personally, I would store the data a little differently, either as comma separated values or as XML (either of which has facilities to cope with newlines and so forth).
There is a nice article here:
http://www.codeproject.com/Articles/415732/Reading-and-Writing-CSV-Files-in-Csharp
which would make your job a lot easier!

Gilmore Sacco 31-Dec-12 5:05am

hello once again. Yes i quite like the idea of comma separation and i implemented it in the writing part as sugessted by Chona1171. now i shall try and read. I dont thing there is a newline command in the variables. It it true i am using it to display them, but not the variables themselves

OriginalGriff 31-Dec-12 5:10am

Depends where they came from - if at any time they were in a multi-line text box for example, the user can add all teh newlines he wants! :laugh:

Gilmore Sacco 31-Dec-12 5:13am

is it possible? since a am implementing a command line application

OriginalGriff 31-Dec-12 5:24am

Without knowing what code you use to read the data and insert it into the class fields I cannot say! :)

sariqkhan 31-Dec-12 8:12am

can you help me sir
http://www.codeproject.com/Questions/519171/showingplusonlyplustheplusfilteredpluscolumnplusin