Check out example codes for "read file line by line c#". It will help you in understanding the concepts better.

Code Example 1

// Read the file and display it line by line.  
System.IO.StreamReader file =   
    new System.IO.StreamReader(@"c:\test.txt");  
while((line = file.ReadLine()) != null)  
{  
    System.Console.WriteLine(line);  
    counter++;  
}

Code Example 2

// To save the text as one string use 'ReadAllText()'
string text = System.IO.File.ReadAllText(@"C:\filepath\file.txt");
// To save each line seperately in an array use 'ReadAllLines()'
string[] lines = System.IO.File.ReadAllLines(@"C:\filepath\file.txt");

Learn ReactJs, React Native from akashmittal.com