67. To check if a number is prime or not Yes: Add all alternate digits No: Multiply all alternate digits

 #include<stdio.h>

void main()

{

        int mul=1,add=0,r,num,i,c=0,digit=1;

        printf("To check if a number is prime or not \nYes: Add all alternate digits \nNo: Multiply all alternate digits\n");

        printf("Enter a number : ");

        scanf("%d",&num);

        for(i=2;i<num;i++)

        {

                if(num%i==0)

                        {

                                c++;

                                break;

                        }

        }

        if(c==0)

                {

                printf("Its a prime number\n");

                for(;num;num=num/10)

                {

                        r=num%10;

                        if(digit%2!=0)

                                add=add+r;

                        digit++;

                }

                printf("%d\n",add);

                }

 

 

 

        else

        {

                printf("Its a non prime number\n");

                for(;num;num=num/10)

                {

                        r=num%10;

                        if(digit%2!=0)

                                mul=mul*r;

                        digit++;

                }

                printf("%d\n",mul);

        }

}