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P. 602
Program 19 Write a program to input a number and using the recursion method, check whether the
number is an emirp number or not.
An emirp number is a number which is prime backwards and forwards. Example : 13 and 31
are both prime numbers. Thus, 13 is an emirp number.
Class name : Emirp
Data Members
int num : to input a number
int rev : stores the reverse of the number n
int flag : is a flag variable
Member Methods
Emirp(int nn) : parameterised constructor to assign num=n
int isprime(int x) : recursive function to check whether the parameter is a
prime number or not
void isEmrip() : calls isprime(int) and checks whether it is an emirp
number or not
1 import java.util.Scanner;
2
3 class Emirp
4 {
5 int num;
6 int rev;
7 int flag;
8
9 Emirp(int nn)
10 {
11 num = nn;
12 rev = 0;
13 flag = 0;
14 }
15
16 int reverse(int n)
17 {
18 int reversedNum = 0;
19 while (n != 0)
20 {
21 reversedNum = reversedNum * 10 + n % 10;
22 n = n / 10;
600 Touchpad Computer Science (Ver. 3.0)-XI
