Age Calculation with nullable death date
using System;
using System.ruponentModel;
class Person
{
DateTime birth;
DateTime? death;
string name;
public TimeSpan Age{
get{
if (death == null){
return DateTime.Now - birth;
}else{
return death.Value - birth;
}
}
}
public Person(string name,DateTime birth,DateTime? death)
{
this.birth = birth;
this.death = death;
this.name = name;
}
public static void Main()
{
Person turing = new Person("A",new DateTime(1913, 2, 23),new DateTime(1954, 6, 7));
Person knuth = new Person("D",new DateTime(1978, 1, 10),null);
}
}Box and unbox for nullable value
using System;
using System.Collections.Generic;
using System.Text;
using System.ruponentModel;
class MainClass
{
static void Main()
{
int? nullable = 5;
object boxed = nullable;
Console.WriteLine(boxed.GetType());
int normal = (int)boxed;
Console.WriteLine(normal);
nullable = (int?)boxed;
Console.WriteLine(nullable);
nullable = new int?();
boxed = nullable;
Console.WriteLine(boxed == null);
nullable = (int?)boxed;
Console.WriteLine(nullable.HasValue);
}
}Boxing And Unboxing for nullable type
using System;
using System.ruponentModel;
class MainClass
{
static void Main()
{
Nullable<int> nullable = 5;
object boxed = nullable;
Console.WriteLine(boxed.GetType());
nullable = (Nullable<int>)boxed;
Console.WriteLine(nullable);
nullable = new Nullable<int>();
boxed = nullable;
Console.WriteLine(boxed == null);
nullable = (Nullable<int>)boxed;
Console.WriteLine(nullable.HasValue);
}
}Convert nullable value to string
using System;
using System.ruponentModel;
class NullableMembers
{
static void Display(Nullable<int> x)
{
Console.WriteLine("HasValue: {0}", x.HasValue);
if (x.HasValue)
{
Console.WriteLine("Value: {0}", x.Value);
Console.WriteLine("Explicit conversion: {0}", (int)x);
}
Console.WriteLine("ToString(): \"{0}\"", x.ToString());
}
static void Main()
{
Nullable<int> x = 5;
x = new Nullable<int>(5);
Console.WriteLine("Instance with value:");
Display(x);
x = new Nullable<int>();
Console.WriteLine("Instance without value:");
Display(x);
}
}Does Nullable value has value
using System;
using System.ruponentModel;
class NullableMembers
{
static void Display(Nullable<int> x)
{
Console.WriteLine("HasValue: {0}", x.HasValue);
if (x.HasValue)
{
Console.WriteLine("Value: {0}", x.Value);
Console.WriteLine("Explicit conversion: {0}", (int)x);
}
}
static void Main()
{
Nullable<int> x = 5;
x = new Nullable<int>(5);
Console.WriteLine("Instance with value:");
Display(x);
x = new Nullable<int>();
Console.WriteLine("Instance without value:");
Display(x);
}
}Function for getting Nullable double value
using System;
public class MainClass{
static double? GetNullableDouble()
{
double? result;
string userInput = Console.ReadLine();
try
{
result = double.Parse(userInput);
}
catch
{
result = null;
}
return result;
}
}Get hash code for nullable value
using System;
using System.ruponentModel;
class NullableMembers
{
static void Display(Nullable<int> x)
{
Console.WriteLine("HasValue: {0}", x.HasValue);
if (x.HasValue)
{
Console.WriteLine("Value: {0}", x.Value);
Console.WriteLine("Explicit conversion: {0}", (int)x);
}
Console.WriteLine("GetHashCode(): {0}", x.GetHashCode());
}
static void Main()
{
Nullable<int> x = 5;
x = new Nullable<int>(5);
Console.WriteLine("Instance with value:");
Display(x);
x = new Nullable<int>();
Console.WriteLine("Instance without value:");
Display(x);
}
}Get value or default value for nullable value
using System;
using System.ruponentModel;
class NullableMembers
{
static void Display(Nullable<int> x)
{
Console.WriteLine("HasValue: {0}", x.HasValue);
if (x.HasValue)
{
Console.WriteLine("Value: {0}", x.Value);
Console.WriteLine("Explicit conversion: {0}", (int)x);
}
Console.WriteLine("GetValueOrDefault(): {0}",x.GetValueOrDefault());
}
static void Main()
{
Nullable<int> x = 5;
x = new Nullable<int>(5);
Console.WriteLine("Instance with value:");
Display(x);
x = new Nullable<int>();
Console.WriteLine("Instance without value:");
Display(x);
}
}Nullable Class Members
using System;
using System.ruponentModel;
class NullableMembers
{
static void Display(Nullable<int> x)
{
Console.WriteLine("HasValue: {0}", x.HasValue);
if (x.HasValue)
{
Console.WriteLine("Value: {0}", x.Value);
Console.WriteLine("Explicit conversion: {0}", (int)x);
}
}
static void Main()
{
Nullable<int> x = 5;
x = new Nullable<int>(5);
Console.WriteLine("Instance with value:");
Display(x);
x = new Nullable<int>();
Console.WriteLine("Instance without value:");
Display(x);
}
}Nullable integer Demo
using System;
using System.ruponentModel;
class NullableDemo
{
static void Main()
{
int? x = null;
x = 5;
if (x != null)
{
int y = x.Value;
Console.WriteLine (y);
}
int z = x ?? 10;
}
}Nullable Try Parse
using System;
using System.ruponentModel;
class NullableTryParse
{
static int? TryParse(string data)
{
int ret;
if (int.TryParse(data, out ret))
{
return ret;
}
else
{
return null;
}
}
static void Main()
{
int? parsed = TryParse("Not valid");
if (parsed != null)
{
Console.WriteLine("Parsed to {0}", parsed.Value);
}
else
{
Console.WriteLine("Couldn"t parse");
}
}
}Nullable value based vector
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
public class Vector
{
public double? R = null;
public double? Theta = null;
public double? ThetaRadians
{
get
{
return (Theta * Math.PI / 180.0);
}
}
public Vector(double? r, double? theta)
{
if (r < 0){
r = -r;
theta += 180;
}
theta = theta % 360;
R = r;
Theta = theta;
}
public static Vector operator +(Vector op1, Vector op2)
{
try
{
double newX = op1.R.Value * Math.Sin(op1.ThetaRadians.Value)+ op2.R.Value * Math.Sin(op2.ThetaRadians.Value);
double newY = op1.R.Value * Math.Cos(op1.ThetaRadians.Value)+ op2.R.Value * Math.Cos(op2.ThetaRadians.Value);
double newR = Math.Sqrt(newX * newX + newY * newY);
double newTheta = Math.Atan2(newX, newY) * 180.0 / Math.PI;
return new Vector(newR, newTheta);
}
catch
{
return new Vector(null, null);
}
}
public static Vector operator -(Vector op1)
{
return new Vector(-op1.R, op1.Theta);
}
public static Vector operator -(Vector op1, Vector op2)
{
return op1 + (-op2);
}
public override string ToString()
{
string rString = R.HasValue ? R.ToString() : "null";
string thetaString = Theta.HasValue ? Theta.ToString() : "null";
return string.Format("({0}, {1})", rString, thetaString);
}
}
class Program
{
static void Main(string[] args)
{
Vector v1 = new Vector(1, 2);
Vector v2 = new Vector(1, 3);
Console.WriteLine("{0} + {1} = {2}", v1, v2, v1 + v2);
Console.WriteLine("{0} - {1} = {2}", v1, v2, v1 - v2);
}
}Partial Comparer for nullable value
using System.Collections.Generic;
using System.ruponentModel;
public static class PartialComparer
{
public static int? Compare<T>(T first, T second)
{
return Compare(Comparer<T>.Default, first, second);
}
public static int? Compare<T>(IComparer<T> comparer,T first,T second)
{
int ret = comparer.rupare(first, second);
if (ret == 0)
{
return null;
}
return ret;
}
}Provide default value for nullable value
using System;
using System.ruponentModel;
class NullableMembers
{
static void Display(Nullable<int> x)
{
Console.WriteLine("HasValue: {0}", x.HasValue);
if (x.HasValue)
{
Console.WriteLine("Value: {0}", x.Value);
Console.WriteLine("Explicit conversion: {0}", (int)x);
}
Console.WriteLine("GetValueOrDefault(10): {0}",x.GetValueOrDefault(10));
}
static void Main()
{
Nullable<int> x = 5;
x = new Nullable<int>(5);
Console.WriteLine("Instance with value:");
Display(x);
x = new Nullable<int>();
Console.WriteLine("Instance without value:");
Display(x);
}
}Reference Compare for nullable value
public static class PartialComparer
{
public static int? ReferenceCompare<T>(T first, T second) where T : class{
if (first == second){
return 0;
}
if (first == null){
return -1;
}
if (second == null){
return 1;
}
return null;
}
}Using the Nullable Modifier
public class MainClass{
static void Main()
{
int? count = null;
do
{
// ...
}
while(count == null);
}
}
