Shortcut Methods from File Class

The following static methods read an entire file into memory in one step:

• File.ReadAllText (returns a string)
• File.ReadAllLines (returns an array of strings)
• File.ReadAllBytes (returns a byte array)

The following static methods write an entire file in one step:

• File.WriteAllText
• File.WriteAllLines
• File.WriteAllBytes
• File.AppendAllText (great for appending to a log file)

ReadLines is like ReadAllLines except that it returns a lazily-evaluated IEnumerable<string>. LINQ is ideal for consuming the results.

The following calculates the number of lines greater than 80 characters in length:

using System;
using System.IO;
using System.Linq;
class Program
{
    static void Main()
    {
        int longLines = File.ReadLines("customer.xml").Count(l => l.Length > 80);

    }
}

AppDomain.CurrentDomain.BaseDirectory returns the application base directory.

To specify a filename relative to this directory, you can call Path.Combine.

using System;
using System.IO;
using System.Linq;
class Program
{
    static void Main()
    {
        string baseFolder = AppDomain.CurrentDomain.BaseDirectory;
        string logoPath = Path.Combine(baseFolder, "customer.xml"); 
        Console.WriteLine(File.Exists(logoPath));
    }
}