If you simply want to give inputs to your program using text file, so you don't need to write them always again and again, then you can just use Console.ReadLine() in case of console app as usual and launch the app using program.exe < inputs.txt.
If you want to do something more complex, like text analysys etc. Then StreamReader might be what you're looking for:
https://docs.microsoft.com/en-us/dotnet … work-4.7.2
A brief example:

using System;
using System.IO;

//...

using (StreamReader sr = new StreamReader(@"PathtoYourFile")) {
string fileContent;
fileContent=sr.readToEnd();
//Do your analysis here
}
//Other code

Or because StreamReader is a stream, you can do also something like this:

using System;
using System.IO;

//...
using (StreamReader sr = new StreamReader(@"PathToYourFile")) {
string currentLine;
while ((currentLine = sr.ReadLine()) != null)
{
//Do your line processing here
}
}
//Other code

Best regards

Rastislav

To read files line by line, there is also File.ReadAllLines(path) that I like, it returns all lines of a file, it's a one liner. See https://docs.microsoft.com/en-us/dotnet … work-4.7.2

You might be interested by overloads of that method

@3:

Is not required, because in case of this while loop:

while ((currentLine = sr.ReadLine()) != null)

The loop will end in case of null value in currentLine.

Checking if string is empty is another thing, it is a part of analysis algorithm which may or may not want it.

Best regards

Rastislav