C#•2w ago

✅ StreamWriter not writing to file

Hello guys, I changed my file properties to "Copy if newer" (I didn't understand why we need to do that, would really appreciate if someone can explain) .... I was able to read a file but when it comes to write to it, it seems that nothing is being written and no exception is being thrown (I added the .close method).

C#
// How to read and write to file in C#
string filePath = Path.GetFullPath("sample.txt");

try
{
    var sr = new StreamReader(filePath);
    var line = sr.ReadLine();
    Console.WriteLine(line);
    sr.Close();
}
catch (Exception e)
{
    Console.WriteLine(e.Message);
}

try
{
    using (var sw = new StreamWriter(filePath, true, Encoding.Unicode))
    {
        sw.WriteLine("Just a new line");
        sw.WriteLine("Just a new line 2");
    }
    
}
catch (Exception e)
{
    Console.WriteLine($"Processing failed: {e.Message}");
}
finally
{
    Console.WriteLine("Finally block executed");
}

C#
// How to read and write to file in C#
string filePath = Path.GetFullPath("sample.txt");

try
{
    var sr = new StreamReader(filePath);
    var line = sr.ReadLine();
    Console.WriteLine(line);
    sr.Close();
}
catch (Exception e)
{
    Console.WriteLine(e.Message);
}

try
{
    using (var sw = new StreamWriter(filePath, true, Encoding.Unicode))
    {
        sw.WriteLine("Just a new line");
        sw.WriteLine("Just a new line 2");
    }
    
}
catch (Exception e)
{
    Console.WriteLine($"Processing failed: {e.Message}");
}
finally
{
    Console.WriteLine("Finally block executed");
}

26 Replies

leowest•2w ago

when you run your app it will create a folder and all files that are in your project set to copy will be copied over to that folder so when you read the file sample.txt you're reading that copy and when u append text you're also appending it to that copy not the file in your project so maybe you're checking the sile in your project

FakerOP•2w ago

ahhh

leowest•2w ago

and not seeing the changes u think its not writing to it?

FakerOP•2w ago

yeah true yeahh I think it's in the debug folder wait need to find it

leowest•2w ago

bin\Debug\net9.0-windows it will be something like this

FakerOP•2w ago

yep

leowest•2w ago

so to explain what copy if newer does it means that it will only copy to the directory if the file that exists there differs from the one u have in your project i.e.: if u add things or remove things from it

FakerOP•2w ago

oh ok, I see, yeah you were right, I can now see the new lines being appended hmm but basically, we would need to reflect those changes back to the file in our project, no ? well here I'm just experimenting but in production etc ?

leowest•2w ago

it depends on what the purpose of the file is

FakerOP•2w ago

ah yeah true, say I would need to have the new contents back in the file in the project, I would need to change from debug mode to release mode, something like that ?

leowest•2w ago

let's say you're learning and you're using it as means to store username and password so yeah u would want to have a common place to store that file so it can be accessible in both scenarios so if u wanted to access the sample.txt in your project u would need to go back a few folders in the path ur giving it as one example

../ = bin
../../ = bin/debug
../../../ = bin/debug/.net9-windows

../ = bin
../../ = bin/debug
../../../ = bin/debug/.net9-windows

but these kind of things however can cause problems if u plan on distributing the app for example because it might not be true that u can find that file in the other target systems by using that path so what is usually recommended is a common folder to store the file such as AppData/roaming for example

FakerOP•2w ago

yep I see

leowest•2w ago

var myAppData = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData), "MyAppName");

var myAppData = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData), "MyAppName");

FakerOP•2w ago

ahh saw the Path.Combine method earlier, this is where it is used

leowest•2w ago

yes its a nice way to merge multiple paths without having to worry if you're using the proper separator for folders which changes depending on the OS i.e.: c:\a\myfile.txt /home/a/myfile.txt

FakerOP•2w ago

yep I see I will just experiment a bit and came back if I have other doubts, thanks !! last question, when we write the GetFolderPath method, we use system folders, like MyDocuments or Desktop or ApplicationData.... can we use a custom folder, like one in our project itself ?

leowest•2w ago

GetFolderPath is a specific method to get the user special paths if you want to write your own path u dont need that

leowest•2w ago

leowest•2w ago

https://learn.microsoft.com/en-us/dotnet/api/system.environment.getfolderpath?view=net-9.0 and here u can see the list of options it can take https://learn.microsoft.com/en-us/dotnet/api/system.environment.specialfolder?view=net-9.0

FakerOP•2w ago

Yep I see, I will have a look, ty !

leowest•2w ago

var myCustomPath = Path.Combine("Data", "sample.txt");

var myCustomPath = Path.Combine("Data", "sample.txt");

FakerOP•2w ago

yeah it worked, I understand what my current working directory was now, why it wasn't working etc, thanks !! By the way, you mentioned earlier, we could do something like

../ = bin
../../ = bin/debug
../../../ = bin/debug/.net9-windows

../ = bin
../../ = bin/debug
../../../ = bin/debug/.net9-windows

But it isn't recommended, the following also:

C#
string workingDirectory = Environment.CurrentDirectory;
string projectDirectory = Directory.GetParent(workingDirectory).Parent.Parent.FullName;
string filePath = Path.Combine(projectDirectory, "Doc/sample.txt");

C#
string workingDirectory = Environment.CurrentDirectory;
string projectDirectory = Directory.GetParent(workingDirectory).Parent.Parent.FullName;
string filePath = Path.Combine(projectDirectory, "Doc/sample.txt");

Isn't recommended because of the file separator since it depends on OS being used; that's why we tend to use the GetFolderPath method?

leowest•2w ago

no Environment.GetFolderPath is a special method specifically for what I described above it has nothing to do with anything else this is not recommended because there is no guarantee that the app u send me will have files in those directories imagine I put your app in c:\ so its at c:\yourApp how would ..\..\..\ work? if there are no parents this is called relative path when you try to access something by going down or up levels

FakerOP•2w ago

Yep I see, I believed my doubts have been cleared 👍

leowest•2w ago

$close

MODiX•2w ago

If you have no further questions, please use /close to mark the forum thread as answered

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✅ StreamWriter not writing to file

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