How To Pass Parameters For Opening Files C#

I am very new to c# and Im having issues trying to understanding this. How to pass a parameter to (or from I tend to confuse the terminology) the main function in order to read a t

Solution 1:

You should have input argument args for your main():

staticvoidMain(string[] args)

As an example:

classProgram {
    staticvoidMain(string[] args) {
        Console.WriteLine("This is the program");
        if (args == null || args.Length == 0) {
            Console.WriteLine("This has no argument");
            Console.ReadKey();
            return;
        }
        Console.WriteLine("This has {0} arguments, the arguments are: ", args.Length);
        for (int i = 0; i < args.Length; ++i)
            Console.WriteLine(args[i]);
        Console.ReadKey();
    }
}

The program will show you if you call the .exe with argument or not:

C:\Release> ConsoleApplication.exe //has no argument
C:\Release> ConsoleApplication.exe Data.txt //has one argument
C:\Release> ConsoleApplication.exe CallWith Data.txt //has two arguments
C:\Release> ConsoleApplication.exe "CallWith Data.txt" //has ONE arguments

In your case, likely the argument is just a single string, thus, putting the input checking on args[0] will be enough:

publicstaticvoidMain(string[] args)
{
    if (args == null || args.Length == 0) {
        Console.WriteLine("Error: please specify the file to read!");
        Console.ReadKey();
        return;
    }

    try {

        StreamReader src = new StreamReader(args[0]);

        while(!src.EndOfStream)
        {
            string line = src.ReadLine();
            Console.WriteLine(line);
        }
    } catch (Exception ex) {
        Console.WriteLine("Error while reading the file! " + ex.ToString());
    }

    Console.ReadKey();    
}

Edit:

Your final solution should look like this (simply put the Main block to the correct namespace and class) and you should use all the usings:

using System;
using System.IO;

namespaceConsoleApplication2 {
    classProgram {
        publicstaticvoidMain(string[] args) {
            if (args == null || args.Length == 0) {
                Console.WriteLine("Error: please specify the file to read!");
                Console.ReadKey();
                return;
            }

            try {

                StreamReader src = new StreamReader(args[0]);

                while (!src.EndOfStream) {
                    string line = src.ReadLine();
                    Console.WriteLine(line);
                }
            } catch (Exception ex) {
                Console.WriteLine("Error while reading the file! " + ex.ToString());
            }

            Console.ReadKey();
        }
    }
}

Solution 2:

You can acces command line arguments from any place of your program using

string[] args = Environment.GetCommandLineArgs();

Also, the simplest way to read all lines in the file is

if (args.Length > 1)    //the 1st is always the path to appstring[] lines = System.IO.File.ReadAllLines(ards[1]);