// keyword_bool.cs
using System;
public class MyClass
{
    static void Main()
    {
        bool i = true;
        char c = '0';
        Console.WriteLine(i);
        i = false;
        Console.WriteLine(i);

        bool Alphabetic = (c > 64 && c < 123);
        Console.WriteLine(Alphabetic);
    }
}

int x = 123;
if (x)   // Invalid in C#
{
    printf("The value of x is nonzero.");
}

int x = 123;
if (x != 0)   // The C# way
{
    Console.Write("The value of x is nonzero.");
}

// keyword_bool_2.cs
using System;
public class BoolTest 
{
    static void Main() 
    {
        Console.Write("Enter a character: "); 
        char c = (char)Console.Read();
        if (Char.IsLetter(c))
        {
            if (Char.IsLower(c))
            {
                Console.WriteLine("The character is lowercase.");
            }
            else
            {
                Console.WriteLine("The character is uppercase.");
            }
        }
        else
        {
            Console.WriteLine("Not an alphabetic character.");
        }
    }
}