Topics

C#•2mo ago

Merineth 🇸🇪

✅ Reading a file

Problem description: In the file TextFileReader.cs (in the folder IO), you will find a code skeleton for the class TextFileReader. Implement the functionality to read text from a text file. It should be possi- ble to use the class from a client (another class), where the client can enter a path to the text file, where the file’s content is returned to the client. In the folder files (in Solution Explorer ), there is a text file textfile.txt containing some rows of text. The relative path to this file (from the code) is files/textfile.txt.

using System.IO;
using System.Runtime.CompilerServices;
using Workshop3.Exceptions;
using static System.Net.WebRequestMethods;

namespace Workshop3.IO
{
    public class TextFileReader
    {
        
    }
}

using System.IO;
using System.Runtime.CompilerServices;
using Workshop3.Exceptions;
using static System.Net.WebRequestMethods;

namespace Workshop3.IO
{
    public class TextFileReader
    {
        
    }
}

How do i go about solving this?

89 Replies

Angius•2mo ago

uh, make a method and have it read a file?

Merineth 🇸🇪•2mo ago

RIght, but my teachers slides aren't really informative in how i do that

Angius•2mo ago

Google would be File class will be useful

Merineth 🇸🇪•2mo ago

I don't understand, isn't #help supposed to get help with c# coding?

Angius•2mo ago

It is, yes But you're also expected to put in the bare minimum of effort yourself And it's clear you didn't even google csharp read file

Merineth 🇸🇪•2mo ago

I'm aware, but i'm completely new to c# I've been trying to find a solution since 8 am this morning don't assume anything

Angius•2mo ago

What did you find and why did it not work?

Merineth 🇸🇪•2mo ago

Well afaik i'm supposed to use a mthod from the Using I/O which is Streamreader to read from a textfile.

Angius•2mo ago

It's one way to do that, sure So what didn't work about that?

Merineth 🇸🇪•2mo ago

This is the only information provided around the subject given to us

No description

Angius•2mo ago

So you have pretty much ready-made code Just need to place it inside of a method in the class you were given

Merineth 🇸🇪•2mo ago

Yes, i attempted that earlier and i got 35 errors.

No description

Angius•2mo ago

Notice how I said "inside of a method" While you placed this code inside of a class $structure

MODiX•2mo ago

namespace Namespace;

[Attribute]
public class Class
{
    public string PublicField;
    private bool _privateField;    

    public int PublicProperty { get; set; }

    public Class() {} // Constructor

    public void Method(int parameter)
    {
        var localVariable = parameter; 

        int LocalMethod(string param) { return 3; }
    } 
}

namespace Namespace;

[Attribute]
public class Class
{
    public string PublicField;
    private bool _privateField;    

    public int PublicProperty { get; set; }

    public Class() {} // Constructor

    public void Method(int parameter)
    {
        var localVariable = parameter; 

        int LocalMethod(string param) { return 3; }
    } 
}

Angius•2mo ago

Here's the naming

Merineth 🇸🇪•2mo ago

I see, so i have to create a method within the class and place the code inside it

Angius•2mo ago

yep

Merineth 🇸🇪•2mo ago

namespace Workshop3.IO
{
    public class TextFileReader
    {


        public void TextFileReaderMethod()
        {
            using (StreamReader sr = File.Opentext("files/textfile.txt"))
            {
                string input = null;
                while ((input = sr.ReadLine() != null))
                {
                    Console.Writeline(input);
                }
            }

        }
    }
}

namespace Workshop3.IO
{
    public class TextFileReader
    {


        public void TextFileReaderMethod()
        {
            using (StreamReader sr = File.Opentext("files/textfile.txt"))
            {
                string input = null;
                while ((input = sr.ReadLine() != null))
                {
                    Console.Writeline(input);
                }
            }

        }
    }
}

Angius•2mo ago

That should work, yes

Merineth 🇸🇪•2mo ago

That did reduce the amount of errors significantly, yea

Merineth 🇸🇪•2mo ago

No description

Merineth 🇸🇪•2mo ago

Severity    Code    Description    Project    File    Line    Suppression State
Error    CS0104    'File' is an ambiguous reference between 'System.Net.WebRequestMethods.File' and 'System.IO.File

Google mentions that i'm using two usingstatements

Angius•2mo ago

Delete this line

Merineth 🇸🇪•2mo ago

Oh yeah that fixed the error Error CS0117 'File' does not contain a definition for 'Opentext' Ah nvm was a typo Okay right it did compile correctly now, i ran the program but i didn't get any output

Merineth 🇸🇪•2mo ago

Essentially i navigate the menu to "Read Text FIle", insert the number 2 but not getting any output hmm

No description

SG97•2mo ago

is your method actually being called? I see 0 references

Merineth 🇸🇪•2mo ago

Good question I'm not entirely sure to be honest

SG97•2mo ago

then it probably is not

Merineth 🇸🇪•2mo ago

Should the method be called within the same class?

SG97•2mo ago

well, that depends, but it depends even more on how you are handling those 1 and 2 inputs probably not within this class

Merineth 🇸🇪•2mo ago

Ah I see, then I most likely will have to navigate to the namespace where the menus are being handled

SG97•2mo ago

assuming the class, but sure

Merineth 🇸🇪•2mo ago

Quick question tho about c#. Can c# generally be summarized as being Classes and objects where each class is a blueprint to instantiate an object with attributes and methods?

Angius•2mo ago

Basically Except you probably meant fields and properties, not attributes Strictly speaking $structure

MODiX•2mo ago

namespace Namespace;

[Attribute]
public class Class
{
    public string PublicField;
    private bool _privateField;    

    public int PublicProperty { get; set; }

    public Class() {} // Constructor

    public void Method(int parameter)
    {
        var localVariable = parameter; 

        int LocalMethod(string param) { return 3; }
    } 
}

namespace Namespace;

[Attribute]
public class Class
{
    public string PublicField;
    private bool _privateField;    

    public int PublicProperty { get; set; }

    public Class() {} // Constructor

    public void Method(int parameter)
    {
        var localVariable = parameter; 

        int LocalMethod(string param) { return 3; }
    } 
}

Merineth 🇸🇪•2mo ago

Hmm weird our teacher strictly says it’s attributes 😭

Angius•2mo ago

Your teacher should not be teaching, then Which is how it usually is, unfortunately

Merineth 🇸🇪•2mo ago

Does C# have similar functions such as scanf in C?

Angius•2mo ago

What does scanf do?

Merineth 🇸🇪•2mo ago

Relatable 😭 It's essentially, a user inputs data and we store the data

Angius•2mo ago

Console.ReadLine() for example

Merineth 🇸🇪•2mo ago

Aaah right, nice! Does that prompt an input from the user?

Angius•2mo ago

yep

Merineth 🇸🇪•2mo ago

Okay so i found the corresponding menu

Merineth 🇸🇪•2mo ago

No description

Merineth 🇸🇪•2mo ago

I'm not entirely sure if it's calling it tho?

It should be possible to use the class from a client (another class), where the client can enter a path to the text file,
where the file’s content is returned to the client

Would this indicate that i have to make a Console.ReadLine() command to accept the filepath to the file the user wants outputted?

namespace Workshop3.IO
{
    public class TextFileReader
    {

        string filepath = @"C:\Users\joal22za\OneDrive - Jonkoping University\OOP\Workshop3\Workshop3\files\textfile.txt";

        void method()
        {
            string[] lines = File.ReadAllLines(filepath);
        }

    }
}

namespace Workshop3.IO
{
    public class TextFileReader
    {

        string filepath = @"C:\Users\joal22za\OneDrive - Jonkoping University\OOP\Workshop3\Workshop3\files\textfile.txt";

        void method()
        {
            string[] lines = File.ReadAllLines(filepath);
        }

    }
}

I also attempted something like this Didn't work tho

canton7•2mo ago

What makes you think that it didn't work?

Merineth 🇸🇪•2mo ago

When i input 2 into the menu, nothing happens

Merineth 🇸🇪•2mo ago

No description

Merineth 🇸🇪•2mo ago

If i press enter now, nothing happens

canton7•2mo ago

You're not showing us the bit of code which control what happens when you enter '2'... Ah, it's this But that's callineg ReadTextFileManu.ReadTextFile, which just calls Show? I don't see anything which calls TextFileReader Psychic code FTW!

Merineth 🇸🇪•2mo ago

Yeah i'm not sure either, the code given to us is made from our teacher All i'm meant to do is finish making the code in "TextFileReader.cs"

canton7•2mo ago

Well, code ain't going to be called if you don't call it

Merineth 🇸🇪•2mo ago

I see. So i have to make sure it's called within the manu when 2 is selected?

canton7•2mo ago

If you want it to be called when you select menu item 2, you need to have some code which calls it when you select menu item 2 It ain't gonna call itself. It can't read your mind

Merineth 🇸🇪•2mo ago

I found the solution provided by the teacher.

Merineth 🇸🇪•2mo ago

No description

Merineth 🇸🇪•2mo ago

And yes, it seems she has modified the "ReadTextFileMenu.cs" Without mentioning in the description of the assignment that we have to do that :)

namespace Workshop3.Menus
{
    public class ReadTextFileMenu : Menu
    {
        public ReadTextFileMenu(string name)
            : base(name)
        {
            Add(new MenuItem("Read Text File", new Command<ReadTextFileMenu>(this, r => r.ReadTextFile())));
        }

        public void ReadTextFile()
        {
            // Clear the console from previous text
            Console.Clear();
            // Asking the user for filepath
            Console.WriteLine("Enter filepath..");
            // Saving the filepath as a string object
            string filepath = Console.ReadLine();
        }
    }
}

namespace Workshop3.Menus
{
    public class ReadTextFileMenu : Menu
    {
        public ReadTextFileMenu(string name)
            : base(name)
        {
            Add(new MenuItem("Read Text File", new Command<ReadTextFileMenu>(this, r => r.ReadTextFile())));
        }

        public void ReadTextFile()
        {
            // Clear the console from previous text
            Console.Clear();
            // Asking the user for filepath
            Console.WriteLine("Enter filepath..");
            // Saving the filepath as a string object
            string filepath = Console.ReadLine();
        }
    }
}

Okay so i wrote some code myself and i successfully made it so the menu accepts an input from the user However, now i want it to output all of the text inside the file How do i call a method inside another class? Do i just create the method inside the class i want and set it to public? And then call that method?

Merineth 🇸🇪•2mo ago

No description

Merineth 🇸🇪•2mo ago

What does this error mean?

canton7•2mo ago

The method is defined inside TextFileReader. You're trying to call that as if it was defined on ReadTextFileMenu

Merineth 🇸🇪•2mo ago

Is that not allowed? Or is it the call to the method within TextFileReader.cs that is the problem? oh woops they have the same name, that might be it

namespace Workshop3.Menus
{
    public class ReadTextFileMenu : Menu
    {
        public ReadTextFileMenu(string name)
            : base(name)
        {
            Add(new MenuItem("Read Text File", new Command<ReadTextFileMenu>(this, r => r.ReadTextFile())));
        }

        public void ReadTextFile()
        {
            // Clear the console from previous text
            Console.Clear();
            // Asking the user for filepath
            Console.WriteLine("Enter filepath..");
            // Saving the filepath as a string object
            string filepath = Console.ReadLine();

            // Call the method inside TextFileReader.cs
            TextFileReader.StreamTextFile(filepath);

            
        }
    }
}


namespace Workshop3.IO
{
    public class TextFileReader
    {
        public static void StreamTextFile(string filepath)
        {
            string str = File.ReadAllText(filepath);
            Console.WriteLine(str);
        }
    }
}

namespace Workshop3.Menus
{
    public class ReadTextFileMenu : Menu
    {
        public ReadTextFileMenu(string name)
            : base(name)
        {
            Add(new MenuItem("Read Text File", new Command<ReadTextFileMenu>(this, r => r.ReadTextFile())));
        }

        public void ReadTextFile()
        {
            // Clear the console from previous text
            Console.Clear();
            // Asking the user for filepath
            Console.WriteLine("Enter filepath..");
            // Saving the filepath as a string object
            string filepath = Console.ReadLine();

            // Call the method inside TextFileReader.cs
            TextFileReader.StreamTextFile(filepath);

            
        }
    }
}


namespace Workshop3.IO
{
    public class TextFileReader
    {
        public static void StreamTextFile(string filepath)
        {
            string str = File.ReadAllText(filepath);
            Console.WriteLine(str);
        }
    }
}

I changed name to "StreamTextFile" But when i try to call the method it can't find it, hmm

Severity    Code    Description    Project    File    Line    Suppression State
Error    CS0120    An object reference is required for the non-static field, method, or property

I added static to my method and it compiled? Not sure why tho HOLY i did it I'm the fucking best This code worked but i'd love if someone could show me how it would look like if i use ReadStream instead of ReadAllText

Becquerel•2mo ago

you can find an example of using FileStream on the MS docs: https://learn.microsoft.com/en-us/dotnet/api/system.io.filestream.read?view=net-8.0

FileStream.Read Method (System.IO)

Reads a block of bytes from the stream and writes the data in a given buffer.

Becquerel•2mo ago

file.readalltext is essentially a convenient wrapper over this IIRC

Merineth 🇸🇪•2mo ago

Okay i got it to work. However if the user inputs a path which doesn't exist i get an error Is it possible to handle this error with an exception ?

Merineth 🇸🇪•2mo ago

No description

Merineth 🇸🇪•2mo ago

Anyone got any idea what i might have done wrong? It successfully catches the problem, and prints "Filepath does not exist" into the terminal but i'm stillö getting exception unhandled? I removed the "throw" inside the catch block. But now when the program closes right after. Is it possible for it to return up to the try statement?

Angius•2mo ago

Right-click the file that's supposed to be read in VS, open properties, set it to be copied always or copied if newer Also, it's generally not a good idea to keep your code on OneDrive

Pobiega•2mo ago

You'd normally do that with a loop, but you cant do that here, because the input (the file path) comes from outside. so to let the exception go is the correct thing to do you'd need to have the loop where you ask the user for the path Also regarding this comment.. We're not here to spoonfeed you answers. We are here to help you learn. Keep that in mind and you'll be fine.

Merineth 🇸🇪•2mo ago

Well asking how to go about solving something hardly counts as being spoon-fed Especially someone being completely new to c#

Pobiega•2mo ago

No absolutely not, but ZZZZ has a very valid point in that making a google search before asking isnt too much to ask from our point either. If you need help understanding what the google results told you, thats fine. Thats why we always ask you to specify what you have tried, where you got stuck, what you need help with

Merineth 🇸🇪•2mo ago

Yes, that's fine. I should've mentioned what i've tried in the post to clarify. I wouldn't ask a question without trying myself first, lol

Pobiega•2mo ago

Yeah that would be great 🙂 That unfortunately is not true for many or even most. But enough of that, you get the point. Did you understand my point above about the re-trying and doing it at the "right place"?

Merineth 🇸🇪•2mo ago

I think i get what you mean, i'm currently trying to relocate the exception handling towards when the user inputs the filepath

Pobiega•2mo ago

👍

Merineth 🇸🇪•2mo ago

By any chance, does visual studio 2022 have an auto formatter for code? I checked the advanced tab and it says CTRL + D or CTRL + F but that doesnt seem to work

Merineth 🇸🇪•2mo ago

I moved the try and catch towards the creating of the streamreader object. However when i do this sr changes to The name 'sr' does not exist in the current context. Why is that the case? Tey both exist in the same namespace and the same class. Shouldn't that be ok?

No description

Merineth 🇸🇪•2mo ago

does the sr object become restricted inside the try block?

Pobiega•2mo ago

sort of. restricted isnt the right word, but you can think about it like that because sr is defined inside a scope, the declaration only exists within that scope so you could define it outside the try, then initialize it (give it a value) inside the try however, if the try fails, sr will still be null so you can't very well read from it Can you think of a way to solve this problem?

Merineth 🇸🇪•2mo ago

Hmm. Well my suspicion would be to move the try block towards the input of the to check if the filepath exists

Pobiega•2mo ago

hint: a try block can contain way more than just a single line of code. alternatively, can you check if the file exists without using try? as in, is there another way that might be easier and not cause the scope issue?

Merineth 🇸🇪•2mo ago

Oh maybe just a simple ifstatement? I looked it up. Seems there is a method called File.Exists

Pobiega•2mo ago

Sure is!

Merineth 🇸🇪•2mo ago

Which seems to return a boolean

Pobiega•2mo ago

sure does!

Merineth 🇸🇪•2mo ago

Nice ! I think i got it to work. Combined an if statement to check if it exists and if not it just retired the same method and asks for an input. Yeah it seems to work perfectly c: Thanks!!

Pobiega•2mo ago

Very nice

Merineth 🇸🇪•2mo ago

How do i mark post as solved?

Pobiega•2mo ago

The same way you did last time. /Close

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