Read A Text File From a URL in .NET Core

Create New .NET Core Project

dotnet new console -o urlreader

Navigate to Project Folder

cd urlreader

Import Dependencies

using System.IO;
using System.Net.Http;
using System.Threading.Tasks;

Create Reader

Create a function in the Program.cs file that will return a StreamReader from the specified URL. Because in this case it will be used inside the Main method which is static, the new function will also have to be static.

static StreamReader URLStream(String fileurl){
    return new StreamReader(new HttpClient().GetStreamAsync(fileurl).Result);
}

Inside the function, we return a StreamReader which is instantiated by creating an HTTPClient and asynchronously executing a GET request which returns a Task<StreamReader>. In order to resolve the object, the Result property needs to be requested.

Reading File Contents

Replace the contents of the Main method with the following

static void Main(string[] args) {
    string line;
    StreamReader s = URLStream(@"https://algs4.cs.princeton.edu/15uf/tinyUF.txt");
    String myline = s.ReadLine(); //First Line
    while((line = s.ReadLine()) != null) //Subsequent Lines
    {
        Console.WriteLine(line);
    }
}

In this case, the format of the first line is different from the others. However, reading the contents of that line is no different than the other lines.

Run The Program

dotnet run

#Expected Output
#4 3
#3 8
#6 5
#9 4
#2 1
#8 9
#5 0
#7 2
#6 1
#1 0
#6 7

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