Console.WriteLine("Enter a double value:"); double d = Console.ReadDouble();
using System.IO; FileStream fs = new FileStream("input.txt", FileMode.Open, FileAccess.Read); StreamReader reader = new StreamReader(fs); double d = reader.ReadDouble(); reader.Close(); fs.Close();In this example, a FileStream and StreamReader are used to read a double value from a file called "input.txt". Overall, the ReadDouble method is a useful tool for converting and reading double-precision floating-point numbers in C#, and is a part of the System package in the C# standard library.