Char - IsControl

Indicates whether the specified Unicode character is categorized as a control character.

Try it

public static void Main()
{
    char [] input = {'E','F','\n','E','F','6','\n','\r'};

    Console.WriteLine("{0}:\t{1}", "Index", "Is Control");

    for (int i = 0; i < input.Length; i++)
    {
		// C# Extension Method: Char - IsControl
		var result = input[i].IsControl();
		
        Console.WriteLine("{0}:\t\t{1}", i, result);
    }
}

View Source 
using System;

public static partial class Extensions
{
    /// <summary>
    ///     Indicates whether the specified Unicode character is categorized as a control character.
    /// </summary>
    /// <param name="c">The Unicode character to evaluate.</param>
    /// <returns>true if  is a control character; otherwise, false.</returns>
    public static Boolean IsControl(this Char c)
    {
        return Char.IsControl(c);
    }
}