?? ????? C#? ????? ??? ???????. ??? ????? ?? ??? ?? ?? ???? ?? ??? ?????. ???(!)? ?????. ????? k? ???? ?? ?? k???! k?? ??? ?? ?? ?? ??? ????.

k!= k * (k-1) *(k-2) *(k-3) *(k-4) *…….3 *2 * 1.

??? ??? ??? ???? ??

?? ?? 4? ??? ????? ??? ????.

?? #1

4! = 4 * (4-1) *(4-2) * (4-3)

4! = 4 * 3 * 2 * 1

4! = 24.

???? 4? ????? 24???

?? #2

6! = 6 * (6-1)* (6-2)* (6-3) * 6-4)* (6-5)

6! = 6*5*4*3*2*1

6! = 720

??? 6? ??? 720???

????? ? ??? ???? ?? ?? ??? ??? ??? ? ????. ??? ??? ?? 0? ????? 1??? ????.

0! =1.

?? ???? n?? ??? ???! ??? n=0? ??? ?? ?? ???? ?? ???? ????. {displaystyle {binom {0}{0}}={frac {0!}{0!0!}}=1.}

???? ??? ?? ??? ??? ???? ? ???? ????? ?????. ?? ??? ???? ??? ??? ?? ????. ?? ?? k? ??? ??? ?? ???? ??? ? ???? ???????. ? ?? ??? ?? k?? ???? ????. ??? ? k?? ?? ?? ??? ?? ? ?? ??? ?? k-1?? ?? ??? ?? ????(? ?? ??? ?? ????? ???) ?? k(k-1)?? ?? ??? ????. , ?? ? ?? ???? k(k-1)(k-2)?? ??? ??, ??? ?? ??? ???? ?? ?? ????. ??? ????? k(k-1)(k-2)(k-3)…3..1.

? ?? ??? ?? ???? ? ? ?? ????? ???? ???? ??? ?????. ??? k?? ????? ?? n?? ??? ??? ??? ??? ?????. ???? k?? ???? k!/(n!.(k-n)!).

????? n?? ????? ??? ? ?? ??? ? ??????

C#? Factorial ?

??? ??? ???? ??? ??? ???? ??? ???? ????.

?? #1

1. ? ???? for ??? ???? ??? ??? ?????.

??:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace Factorial
{
class Program
{
static void Main()
{
int a = 7;
int fact = 1;
for (int x = 1; x <= a; x++)
{
fact *= x;
}
Console.WriteLine(fact);
Console.ReadLine();
}
}
}

? ????? ?? ??? ??? ??? ????? for ??? ???? ??? ?????.

??:

2. ? ???? ???? ???? ?? ???? ??? ??? ? ????.

??:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using? System.Threading.Tasks;
namespace FactorialExample
{
class Program
{
static void Main()
{
Console.WriteLine("Enter the number: ");
int a = int.Parse(Console.ReadLine());
int fact = 1;
for (int x = 1; x <= a; x++)
{
fact *= x;
}
Console.WriteLine(fact);
Console.ReadLine();
}
}
}

??:

?? #2

1. ? ???? for ??? ???? ??? ??? ?????.

??:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace Factorial
{
class Program
{
static void Main()
{
int a = 10;
int fact = 1;
while (true)
{
Console.Write(a);
if (a == 1)
{
break;
}
Console.Write("*");
fact *= a;
a--;
}
Console.WriteLine(" = {0}", fact);
Console.ReadLine();
}
}
}

??:

2.?? ???? while ??? ???? ??? ??? ?????.

??:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace FactorialExample
{
class Program
{
static void Main()
{
Console.WriteLine("Enter the number: ");
int a = int.Parse(Console.ReadLine());
int fact = 1;
while(true)
{
Console.Write(a);
if(a==1)
{
break;
}
Console.Write("*");
fact *= a;
a--;
}
Console.WriteLine(" = {0}", fact);
Console.ReadLine();
}
}
}

??:

?? #3

1. ? ???? do-while? ???? ??? ??? ?????.

??:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace Factorial
{
class Program
{
static void Main()
{
int a = 6;
int fact = 1;
do
{
fact *= a;
a--;
} while (a > 0);
Console.WriteLine("Factorial = {0}", fact);
Console.ReadLine();
}
}
}

??:

2. ? ???? do-while? ???? ??? ??? ?????.

??:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace FactorialExample
{
class Program
{
static void Main()
{
Console.Write("Enter the number: ");
int a = int.Parse(Console.ReadLine());
int fact = 1;
do
{
fact *= a;
a--;
} while (a > 0);
Console.WriteLine("Factorial = {0}", fact);
Console.ReadLine();
}
}
}

??:

?? #4

1. ? ???? ?? ??? ???? ??? ??? ?????.

??:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace Factorial
{
class Program
{
static void Main()
{
int n= 5;
long fact = Fact(n);
Console.WriteLine("factorial is {1}", n, fact);
Console.ReadKey();
}
private static long Fact(int n)
{
if (n == 0)
{
return 1;
}
return n * Fact(n - 1);
}
}
}

?? ???? ??? ???? ??? ??? ?????. ?? ?? ?? ?? ????? ?? ??? ??? ???? ????. ??? ??? ??? ??? ??? ??? ??? ?? ???? ???.

??:

2.?? ???? ?? ??? ???? ??? ??? ?????.

??:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace FactorialExample
{
class Program
{
static void Main()
{
Console.WriteLine("Enter the number");
int n = Convert.ToInt32(Console.ReadLine());
long fact = Fact(n);
Console.WriteLine("factorial is {1}", n, fact);
Console.ReadKey();
}
private static long Fact(int n)
{
if (n == 0)
{
return 1;
}
return n * Fact(n - 1);
}
}
}

??:

??

??? ????? ??? ???, ??, ??? ?? ?? ???? ?? ????, ?? for, while, do-while, function? ?? ?? ??? ???? ?? ??? ????? ??? ? ?? ?????. ?

? ??? C#? ????? ?? ?????. ??? ??? PHP ??? ????? ?? ?? ??? ?????!