Tuesday, October 11, 2011

C Program to find twin prime numbers

#include<stdio.h>
#include<conio.h>
void main()
{
  int n,i,k,r,a[50],x;
  clrscr();
  printf(" Enter Range : ");
  scanf("%d",&r);
  i=1;
  x=0;
  while(i<=r)
  {
     k=0;n=1;
     while(n<=i)
     {
        if(i%n==0)
            k++;
            n++;
     }
     if(k==2)
     {
        a[x]=i;
        x++;
     }
     i++;
  }

  for(n=0;n<x;n++)
  {
      if(a[n+1]-a[n]==2)
      printf("\n %d and %d are twin prime numbers ",a[n],a[n+1]);
  }
  getch();
}