Here below a little program in Oxygene that implements 2 classes (in fact, they are 3). There is the main class, called Fiborial (Fibo(nnacci)+(Facto)rial) that implements the Fibonacci and the Factorial algorithms in two ways, one Recursive (using recursion) and the other Imperative (using loops and states). The second class is just an instance class that does the same thing, but its there just to show the difference between static and instance classes, and finally the third one (which will not appear in other languages) is the Program class which has the static execution method "Main".
You can also find 3 more little examples at the bottom. One prints out the Factorial's Series and Fibonacci's Series, the second one just shows a class that mixes both: static and instance members, and finally the third one that uses different return types (including System.Numerics.BigInteger) for the Factorial method to compare the timing and result.
As with the previous posts, you can copy and paste the code below in your favorite IDE/Editor and start playing and learning with it. This little "working" program will teach you some more basics of the Programming Language.
There are some "comments" on the code added just to tell you what are or how are some features called. In case you want to review the theory, you can read my previous post, where I give a definition of each of the concepts mentioned on the code. You can find it here: http://carlosqt.blogspot.com/2011/01/new-series-factorial-and-fibonacci.html
The Fiborial Program
// Factorial and Fibonacci in Delphi Prism
namespace FiborialDelphi;
interface
uses
System,
System.Diagnostics,
System.Collections.Generic,
System.Numerics;
type
// Static Class
StaticFiborial = public static class
private
// Static/Class Field
class var
fClassName: string;
public
// Static/Class Constructor
class constructor;
// Static/Class Method - Factorial Recursive
class method FactorialR(n: integer): BigInteger;
// Static/Class Method - Factorial Imperative
class method FactorialI(n: integer): BigInteger;
// Static/Class Method - Fibonacci Recursive
class method FibonacciR(n: integer): Int64;
// Static/Class Method - Fibonacci Imperative
class method FibonacciI(n: integer): Int64;
// Static/Class Method - Benchmarking Algorithms
class method BenchmarkAlgorithm(algorithm: integer; values: List<integer>);
end;
type
// Instance Class
InstanceFiborial = public class
private
// Instance Field
var
fClassName: string;
public
// Instance Constructor
constructor;
// Instance Method - Factorial Recursive
method FactorialR(n: integer): BigInteger;
// Instance Method - Factorial Imperative
method FactorialI(n: integer): BigInteger;
// Instance Method - Fibonacci Recursive
method FibonacciR(n: integer): Int64;
// Instance Method - Fibonacci Imperative
method FibonacciI(n: integer): Int64;
end;
type
ConsoleApp = class
public
class method Main(args: array of string);
end;
implementation
// Static/Class Constructor
class constructor StaticFiborial;
begin
fClassName := 'Static/Class Constructor';
Console.WriteLine(fClassName);
end;
// Static/Class Method - Factorial Recursive
class method StaticFiborial.FactorialR(n: integer): BigInteger;
begin
if n = 1 then
result := 1
else
result := n * FactorialR(n - 1);
end;
// Static/Class Method - Factorial Imperative
class method StaticFiborial.FactorialI(n: integer): BigInteger;
var
res: BigInteger := 1;
begin
for i:integer := n downto 1 step 1 do
res := res * i;
result := res;
end;
// Static/Class Method - Fibonacci Recursive
class method StaticFiborial.FibonacciR(n: integer): Int64;
begin
if n < 2 then
result := 1
else
result := FibonacciR(n - 1) + FibonacciR(n - 2);
end;
// Static/Class Method - Fibonacci Imperative
class method StaticFiborial.FibonacciI(n: integer): Int64;
var
tmp, pre, cur: Int64;
begin
tmp := 0;
pre := 1;
cur := 1;
for i: integer := 2 to n step 1 do
begin
tmp := cur + pre;
pre := cur;
cur := tmp;
end;
result := cur;
end;
// Static Method - Benchmarking Algorithms
class method StaticFiborial.BenchmarkAlgorithm(algorithm: integer; values: List<integer>);
var
timer: StopWatch;
i, testValue: integer;
facTimeResult: BigInteger := 0;
fibTimeResult: Int64 := 0;
begin
i := 0;
testValue := 0;
timer := new StopWatch();
// 'switch/case' Flow Constrol Statement
case algorithm of
1: begin
Console.WriteLine(''#10'Factorial Imperative:');
// 'For' Loop Statement
for i := 0 to values.Count - 1 step 1 do
begin
testValue := values[i];
// Taking Time
timer.Start();
facTimeResult := FactorialI(testValue);
timer.Stop();
// Getting Time
Console.WriteLine(' ({0}) = {1}', testValue, timer.Elapsed);
end;
end;
2: begin
Console.WriteLine(''#10'Factorial Recursive:');
// 'While' Loop Statement
while i < values.Count do
begin
testValue := values[i];
// Taking Time
timer.Start();
facTimeResult := FactorialR(testValue);
timer.Stop();
// Getting Time
Console.WriteLine(' ({0}) = {1}', testValue, timer.Elapsed);
inc(i);
end;
end;
3: begin
Console.WriteLine(''#10'Fibonacci Imperative:');
// 'Repeat/Do' Loop Statement
repeat
testValue := values[i];
// Taking Time
timer.Start();
facTimeResult := FibonacciI(testValue);
timer.Stop();
// Getting Time
Console.WriteLine(' ({0}) = {1}', testValue, timer.Elapsed);
inc(i);
until i = values.Count - 1
end;
4: begin
Console.WriteLine(''#10'Fibonacci Recursive:');
// 'For Each' Loop Statement
for each item in values do
begin
testValue := item;
// Taking Time
timer.Start();
facTimeResult := FibonacciR(testValue);
timer.Stop();
// Getting Time
Console.WriteLine(' ({0}) = {1}', testValue, timer.Elapsed);
end;
end;
else Console.WriteLine('DONG!');
end;
end;
// Instance Constructor
constructor InstanceFiborial;
begin
self.fClassName := 'Instance Constructor';
Console.WriteLine(self.fClassName);
end;
// Instance Method - Factorial Recursive
method InstanceFiborial.FactorialR(n: integer): BigInteger;
begin
// Calling Static Method
result := StaticFiborial.FactorialR(n);
end;
// Instance Method - Factorial Imperative
method InstanceFiborial.FactorialI(n: integer): BigInteger;
begin
// Calling Static Method
result := StaticFiborial.FactorialI(n);
end;
// Instance Method - Fibonacci Recursive
method InstanceFiborial.FibonacciR(n: integer): Int64;
begin
// Calling Static Method
result := StaticFiborial.FibonacciR(n);
end;
// Instance Method - Fibonacci Imperative
method InstanceFiborial.FibonacciI(n: integer): Int64;
begin
// Calling Static Method
result := StaticFiborial.FibonacciI(n);
end;
class method ConsoleApp.Main(args: array of string);
var
values: List<integer>;
ff: InstanceFiborial;
begin
Console.WriteLine(''#10'Static Class');
// Calling Static Class and Methods
// No instantiation needed. Calling method directly from the class
Console.WriteLine('FacImp(5) = {0}', StaticFiborial.FactorialI(5));
Console.WriteLine('FacRec(5) = {0}', StaticFiborial.FactorialR(5));
Console.WriteLine('FibImp(11)= {0}', StaticFiborial.FibonacciI(11));
Console.WriteLine('FibRec(11)= {0}', StaticFiborial.FibonacciR(11));
Console.WriteLine(''#10'Instance Class');
// Calling Instance Class and Methods
// Need to instantiate before using. Calling method from instantiated object
ff := new InstanceFiborial();
Console.WriteLine('FacImp(5) = {0}', ff.FactorialI(5));
Console.WriteLine('FacRec(5) = {0}', ff.FactorialR(5));
Console.WriteLine('FibImp(11)= {0}', ff.FibonacciI(11));
Console.WriteLine('FibRec(11)= {0}', ff.FibonacciR(11));
// Create a (generic) list of integer values to test
// From 5 to 50 by 5
values := new List<integer>();
for i:integer := 5 to 50 step 5 do
values.Add(i);
// Benchmarking Fibonacci
// 1 = Factorial Imperative
StaticFiborial.BenchmarkAlgorithm(1, values);
// 2 = Factorial Recursive
StaticFiborial.BenchmarkAlgorithm(2, values);
// Benchmarking Factorial
// 3 = Fibonacci Imperative
StaticFiborial.BenchmarkAlgorithm(3, values);
// 4 = Fibonacci Recursive
StaticFiborial.BenchmarkAlgorithm(4, values);
// Stop and Exit
Console.Read();
end;
end.
And the Output is:
Humm, looks like Fibonnaci's algorithm implemented using recursion is definitively more complex than the others 3 right? I will grab these results for this and each of the upcoming posts to prepare a comparison of time execution between all the programming languages, then we will be able to talk about the algorithm's complexity as well.
Printing the Factorial and Fibonacci Series
namespace FiborialSeries;
interface
uses
System,
System.Text,
System.Numerics;
type
Fiborial = static class
public
class method GetFactorialSeries(n: integer): string;
class method GetFibonnaciSeries(n: integer): string;
class method Factorial(n: integer): BigInteger;
class method Fibonacci(n: integer): Int64;
end;
type
ConsoleApp = class
public
class method Main(args: array of string);
end;
implementation
class method Fiborial.GetFactorialSeries(n: integer): string;
var
// Using a StringBuilder as a list of string elements
series: StringBuilder;
begin
// Create the String that will hold the list
series := new StringBuilder();
// We begin by concatenating the number you want to calculate
// in the following format: "!# ="
series.Append('!');
series.Append(n);
series.Append(' = ');
// We iterate backwards through the elements of the series
for i: integer := n downto 1 do
begin
// and append it to the list
series.Append(i);
if i > 1 then
series.Append(' * ')
else
series.Append(' = ');
end;
// Get the result from the Factorial Method
// and append it to the end of the list
series.Append(Factorial(n));
// return the list as a string
result := series.ToString();
end;
class method Fiborial.GetFibonnaciSeries(n: integer): string;
var
// Using a StringBuilder as a list of string elements
series: StringBuilder;
begin
// Create the String that will hold the list
series := new StringBuilder();
// We begin by concatenating the first 3 values which
// are always constant
series.Append('0, 1, 1');
// Then we calculate the Fibonacci of each element
// and add append it to the list
for i: integer := 2 to n do
begin
if i < n then
series.Append(', ')
else
series.Append(' = ');
series.Append(Fibonacci(i));
end;
// return the list as a string
result := series.ToString();
end;
class method Fiborial.Factorial(n: integer): BigInteger;
begin
if n = 1 then
result := 1
else
result := n * Factorial(n - 1);
end;
class method Fiborial.Fibonacci(n: integer): Int64;
begin
if n < 2 then
result := 1
else
result := Fibonacci(n - 1) + Fibonacci(n - 2);
end;
class method ConsoleApp.Main(args: array of string);
begin
// Printing Factorial Series
Console.WriteLine();
Console.WriteLine(Fiborial.GetFactorialSeries(5));
Console.WriteLine(Fiborial.GetFactorialSeries(7));
Console.WriteLine(Fiborial.GetFactorialSeries(9));
Console.WriteLine(Fiborial.GetFactorialSeries(11));
Console.WriteLine(Fiborial.GetFactorialSeries(40));
// Printing Fibonacci Series
Console.WriteLine();
Console.WriteLine(Fiborial.GetFibonnaciSeries(5));
Console.WriteLine(Fiborial.GetFibonnaciSeries(7));
Console.WriteLine(Fiborial.GetFibonnaciSeries(9));
Console.WriteLine(Fiborial.GetFibonnaciSeries(11));
Console.WriteLine(Fiborial.GetFibonnaciSeries(40));
Console.Read();
end;
end.
And the Output is:
Mixing Instance and Static Members in the same Class
We can also define instance classes that have both, instance and static members such as: fields, properties, constructors, methods, etc. However, we cannot do that if the class is marked as static because of the features mentioned in the previous post:
The main features of a static class are:
- They only contain static members.
- They cannot be instantiated.
- They are sealed.
- They cannot contain Instance Constructors
namespace FiborialExtrasDelphi2;
// Instance Classes can have both: static and instance members.
// However, Static Classes only allow static members to be defined.
// If you declare our next example class as static
// (static class Fiborial) you will get the following compile error
// Error: cannot declare instance members in a static class
interface
// Instance Class
type Fiborial = class
private
// Instance Field
var fInstanceCount: integer;
// Static Field
class var fStaticCount: integer;
public
// Instance Read-Only Property
// Within instance members, you can always use
// the "this" reference pointer to access your (instance) members.
property InstanceCount : integer read self.fInstanceCount;
// Static Read-Only Property
// Remeber that Properties are Methods to the CLR, so, you can also
// define static properties for static fields.
// As with Static Methods, you cannot reference your class members
// with the "this" reference pointer since static members are not
// instantiated.
class property StaticCount : integer read fStaticCount;
// Instance Constructor
constructor;
// Static Constructor
class constructor;
// Instance Method
method Factorial(n: integer);
// Static Method
class method Fibonacci(n: integer);
end;
type ConsoleApp = class
public
class method Main(args: array of string);
end;
implementation
// Instance Constructor
constructor Fiborial;
begin
self.fInstanceCount := 0;
Console.WriteLine(''#10'Instance Constructor {0}', self.fInstanceCount);
end;
// Static/Class Constructor
class constructor Fiborial;
begin
fStaticCount := 0;
Console.WriteLine(''#10'Static Constructor {0}', fStaticCount);
end;
// Instance Method
method Fiborial.Factorial(n: integer);
begin
inc(self.fInstanceCount);
Console.WriteLine(''#10'Factorial({0})', n);
end;
// Static Method
class method Fiborial.Fibonacci(n: integer);
begin
inc(fStaticCount);
Console.WriteLine(''#10'Fibonacci({0})', n);
end;
class method ConsoleApp.Main(args: array of string);
begin
// Calling Static Constructor and Methods
// No need to instantiate
Fiborial.Fibonacci(5);
// Calling Instance Constructor and Methods
// Instance required
var fib := new Fiborial();
fib.Factorial(5);
Fiborial.Fibonacci(15);
fib.Factorial(5);
// Calling Instance Constructor and Methods
// for a second object
var fib2 := new Fiborial();
fib2.Factorial(5);
Console.WriteLine();
// Calling Static Property
Console.WriteLine('Static Count = {0}', Fiborial.StaticCount);
// Calling Instance Property of object 1 and 2
Console.WriteLine('Instance 1 Count = {0}', fib.InstanceCount);
Console.WriteLine('Instance 2 Count = {0}', fib2.InstanceCount);
Console.Read();
end;
end.
And the Output is:
Factorial using System.Int64, System.Double, System.Numerics.BigInteger
The Factorial of numbers over 20 are massive!
For instance: !40 = 815915283247897734345611269596115894272000000000!
Because of this, the previous version of this program was giving the "wrong" result
!40 = -70609262346240000 when using "long" (System.Int64) type, but it was on my previous post in VB.NET that I realized about this faulty code, because instead of giving me a wrong value, VB.NET execution thrown an Overflow Exception when using the "Long" (System.Int64) type.
My first idea was to use ulong and ULong, but both failed for "big" numbers. I then used Double (double floating point) type and got no more exception/wrong result. The result of the factorial was now correct !40 = 1.1962222086548E+56, but still I wanted to show the Integer value of it, so I did some research and found that there is a new System::Numerics::BigInteger class in the .NET Framework 4.0. Adding the reference to the project and using this new class as the return type of the Factorial methods, I was able to get the result I was expecting.
!40 = 815915283247897734345611269596115894272000000000
What I also found was that using different types change the time the algorithm takes to finish:
System.Int64 < System.Double < System.Numerics.BigInteger
Almost by double!
To illustrate what I just "tried" to say, lets have a look at the following code and the output we get.
namespace FiborialExtrasDelphi3;
interface
uses
System,
System.Numerics,
System.Diagnostics;
type
ConsoleApp = class
public
class method Main(args: array of string);
class method FactorialInt64(n: integer): Int64;
class method FactorialDouble(n: integer): Double;
class method FactorialBigInteger(n: integer): BigInteger;
end;
implementation
class method ConsoleApp.Main(args: array of string);
var
timer: StopWatch;
facIntResult: System.Int64 := 0;
facDblResult: System.Double := 0;
facBigResult: System.Numerics.BigInteger := 0;
begin
timer := new StopWatch();
Console.WriteLine(''#10'Factorial using Int64');
for i: integer := 5 to 50 step 5 do
begin
timer.Start();
facIntResult := FactorialInt64(i);
timer.Stop();
Console.WriteLine(' ({0}) = {1} : {2}', i, timer.Elapsed, facIntResult);
end;
Console.WriteLine(''#10'Factorial using Double');
for i: integer := 5 to 50 step 5 do
begin
timer.Start();
facDblResult := FactorialDouble(i);
timer.Stop();
Console.WriteLine(' ({0}) = {1} : {2}', i, timer.Elapsed, facDblResult);
end;
Console.WriteLine(''#10'Factorial using BigInteger');
for i: integer := 5 to 50 step 5 do
begin
timer.Start();
facBigResult := FactorialBigInteger(i);
timer.Stop();
Console.WriteLine(' ({0}) = {1} : {2}', i, timer.Elapsed, facBigResult);
end;
Console.Read();
end;
class method ConsoleApp.FactorialInt64(n: integer): Int64;
begin
if n = 1 then
result := 1
else
result := n * FactorialInt64(n - 1);
end;
class method ConsoleApp.FactorialDouble(n: integer): Double;
begin
if n = 1 then
result := 1
else
result := n * FactorialDouble(n - 1);
end;
class method ConsoleApp.FactorialBigInteger(n: integer): BigInteger;
begin
if n = 1 then
result := 1
else
result := n * FactorialBigInteger(n - 1);
end;
end.
NOTE: you need to manually add a reference to the System.Numerics.dll assembly to your project so you can add it to your code.
And the Output is:
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