please send me code of Circular Prime program in C# or Java

Try the following C# program :

using System;

using System.Collections.Generic;

class Program

{

static void Main()

{

int max = 999999;

List primes = GetPrimes(max); // get all 6 digit primes

Console.WriteLine("The circular primes under {0} are:\n", max + 1);

foreach(int prime in primes)

{

if(CantBeCircular(prime)) continue;

int next = prime;

bool isCircular = true;

while(true)

{

next = Rotate(next);

if (next == prime) break;

if (!primes.Contains(next))

{

isCircular = false;

break;

}

if(isCircular) Console.WriteLine(prime);

}

Console.ReadKey();

}

static List GetPrimes(int max)

{

// uses Sieve of Eratosthenes algorithm

List primes = new List();

if (max < 2) return primes;

bool[] isntPrime = new bool[max + 1]; // all false by default

int final = (int)Math.Sqrt(max);

for(int i = 2; i <= final; i++)

{

if(!isntPrime[i])

{

for(int j = i * i; j <= max; j += i) isntPrime[j] = true;

}

for(int i = 2; i <= max ; i++)

{

if(!isntPrime[i]) primes.Add(i);

}

return primes;

}

static bool CantBeCircular(int number)

{

// if number contains at least one digit which is even or 5 then it can't be circular

// the only exceptions to this are the numbers 2 and 5 themselves

if (number == 2 || number == 5) return false;

while (number > 0)

{

int digit = number % 10;

if (digit % 2 == 0 || digit == 5) return true;

number /= 10;

}

return false;

}

static int Rotate(int number)

{

if (number < 10) return number;

int total = 0;

int multiplier = 10;

while (number > 9)

{

total += (number % 10) * multiplier;

multiplier *= 10;

number /= 10;

}

total += number % 10;

return total;

}

1 Reply

Know the answer? Post it — somebody with the same question will find it here.

Vulpes14y ago
Try the following C# program :

using System;
using System.Collections.Generic;

class Program
{
static void Main()
{
int max = 999999;
List primes = GetPrimes(max); // get all 6 digit primes
Console.WriteLine("The circular primes under {0} are:\n", max + 1);

foreach(int prime in primes)
{
if(CantBeCircular(prime)) continue;
int next = prime;
bool isCircular = true;

while(true)
{
next = Rotate(next);
if (next == prime) break;
if (!primes.Contains(next))
{
isCircular = false;
break;
}
}

if(isCircular) Console.WriteLine(prime);
}

Console.ReadKey();
}

static List GetPrimes(int max)
{
// uses Sieve of Eratosthenes algorithm
List primes = new List();
if (max < 2) return primes;

bool[] isntPrime = new bool[max + 1]; // all false by default
int final = (int)Math.Sqrt(max);

for(int i = 2; i <= final; i++)
{
if(!isntPrime[i])
{
for(int j = i * i; j <= max; j += i) isntPrime[j] = true;
}
}

for(int i = 2; i <= max ; i++)
{
if(!isntPrime[i]) primes.Add(i);
}

return primes;
}

static bool CantBeCircular(int number)
{
// if number contains at least one digit which is even or 5 then it can't be circular
// the only exceptions to this are the numbers 2 and 5 themselves

if (number == 2 || number == 5) return false;

while (number > 0)
{
int digit = number % 10;
if (digit % 2 == 0 || digit == 5) return true;
number /= 10;
}

return false;
}

static int Rotate(int number)
{
if (number < 10) return number;

int total = 0;
int multiplier = 10;

while (number > 9)
{
total += (number % 10) * multiplier;
multiplier *= 10;
number /= 10;
}

total += number % 10;
return total;
}
}