[c#] How to read existing text files without defining path

Most of the examples shows how to read text file from exact location (f.e. "C:\Users\Owner\Documents\test1.txt"). But, how to read text files without writing full path, so my code would work when copied to other computers. With visual studio I added 2 text files to project (console project) and don't know best way to read those files. Hope I described my problem clearly. Maybe I needed to add those txt files differentely (like directly to same folder as .exe file)?

As your project is a console project you can pass the path to the text files that you want to read via the string[] args

static void Main(string[] args)
{
}

Within Main you can check if arguments are passed

if (args.Length == 0){ System.Console.WriteLine("Please enter a parameter");}

Extract an argument

string fileToRead = args[0];

Nearly all languages support the concept of argument passing and follow similar patterns to C#.

For more C# specific see http://msdn.microsoft.com/en-us/library/vstudio/cb20e19t.aspx

There are many ways to get a path. See CurrentDirrectory mentioned. Also, you can get the full file name of your application by using Assembly.GetExecutingAssembly().Location and then use Path class to get a directory name.

This will load a file in working directory:

        static void Main(string[] args)
        {
            string fileName = System.IO.Path.GetFullPath(Directory.GetCurrentDirectory() + @"\Yourfile.txt");

            Console.WriteLine("Your file content is:");
            using (StreamReader sr = File.OpenText(fileName))
            {
                string s = "";
                while ((s = sr.ReadLine()) != null)
                {
                    Console.WriteLine(s);
                }
            }

            Console.ReadKey();
        }

If your using console you can also do this.It will prompt the user to write the path of the file(including filename with extension).

        static void Main(string[] args)
        {

            Console.WriteLine("****please enter path to your file****");
            Console.Write("Path: ");
            string pth = Console.ReadLine();
            Console.WriteLine();
            Console.WriteLine("Your file content is:");
            using (StreamReader sr = File.OpenText(pth))
            {
                string s = "";
                while ((s = sr.ReadLine()) != null)
                {
                    Console.WriteLine(s);
                }
            }

            Console.ReadKey();
        }

If you use winforms for example try this simple example:

        private void button1_Click(object sender, EventArgs e)
        {
            string pth = "";
            OpenFileDialog ofd = new OpenFileDialog();

            if (ofd.ShowDialog() == DialogResult.OK)
            {
                pth = ofd.FileName;
                textBox1.Text = File.ReadAllText(pth);
            }
        }

If your application is a web service, Directory.CurrentDirectory doesn't work.

Use System.IO.Path.Combine(System.AppDomain.CurrentDomain.BaseDirectory, "yourFileName.txt")) instead.

You absolutely need to know where the files to be read can be located. However, this information can be relative of course so it may be well adapted to other systems.

So it could relate to the current directory (get it from Directory.GetCurrentDirectory()) or to the application executable path (eg. Application.ExecutablePath comes to mind if using Windows Forms or via Assembly.GetEntryAssembly().Location) or to some special Windows directory like "Documents and Settings" (you should use Environment.GetFolderPath() with one element of the Environment.SpecialFolder enumeration).

Note that the "current directory" and the path of the executable are not necessarily identical. You need to know where to look!

In either case, if you need to manipulate a path use the Path class to split or combine parts of the path.

You need to decide which directory you want the file to be relative to. Once you have done that, you construct the full path like this:

string fullPathToFile = Path.Combine(dir, fileName);

If you don't supply the base directory dir then you will be at the total mercy of whatever happens to the working directory of your process. That is something that can be out of your control. For example, shortcuts to your application may specify it. Using file dialogs can change it.

For a console application it is reasonable to use relative files directly because console applications are designed so that the working directory is a critical input and is a well-defined part of the execution environment. However, for a GUI app that is not the case which is why I recommend you explicitly convert your relative file name to a full absolute path using some well-defined base directory.

Now, since you have a console application, it is reasonable for you to use a relative path, provided that the expectation is that the files in question will be located in the working directory. But it would be very common for that not to be the case. Normally the working directory is used to specify where the user's input and output files are to be stored. It does not typically point to the location where the program's files are.

One final option is that you don't attempt to deploy these program files as external text files. Perhaps a better option is to link them to the executable as resources. That way they are bound up with the executable and you can completely side-step this issue.

When you provide a path, it can be absolute/rooted, or relative. If you provide a relative path, it will be resolved by taking the working directory of the running process.

Example:

string text = File.ReadAllText("Some\\Path.txt"); // relative path

The above code has the same effect as the following:

string text = File.ReadAllText(
    Path.Combine(Environment.CurrentDirectory, "Some\\Path.txt"));

If you have files that are always going to be in the same location relative to your application, just include a relative path to them, and they should resolve correctly on different computers.