Nullable bool Types : Nulllable : Data Types C# Source Code

    
 
using System;
using System.Collections.Generic;
using System.Text;

class DatabaseReader {
    // Nullable data field.
    public int? numbericValue;
    public bool? boolValue = true;

    // Note the nullable return type. 
    public int? GetIntFromDatabase() { return numbericValue; }

    // Note the nullable return type. 
    public bool? GetBoolFromDatabase() { return boolValue; }
}

class Program {
    static void Main(string[] args) {
        DatabaseReader dr = new DatabaseReader();

        int? i = dr.GetIntFromDatabase();
        if (i.HasValue)
            Console.WriteLine("Value of 'i' is: {0}", i);
        else
            Console.WriteLine("Value of 'i' is undefined.");
        // Get bool from 'database'.
        bool? b = dr.GetBoolFromDatabase();
        if (b != null)
            Console.WriteLine("Value of 'b' is: {0}", b);
        else
            Console.WriteLine("Value of 'b' is undefined.");
        // If the value from GetIntFromDatabase() is null, 
        // assign local variable to 100.
        int? myData = dr.GetIntFromDatabase() ?? 100;
        Console.WriteLine("Value of myData: {0}", myData);
    }
}