Program for checking whether input number is Prime or not
     #include<stdio.h>   #include<conio.h>   void main()   {   int n,n1,i;   printf("\nEnter any positive integer number to check");   scanf("%d",&n);   if(n==1 || n==2)   printf("\nThe number is Prime");   else   {   i=2;   while(i<=n)   {   if(n%i==0)   break;   i++;   }   if(n==i)   printf("\nThe Number is Prime");   else   printf("\nThe Number is Not Prime");   }   printf("\nPress any key to continue...");   getch();   }       Output     Enter any positive integer number to check 4     The Number is Not Prime   Press any key to continue...   Enter any positive integer number to check   7   The Number is Prime   Press any key to continue...