#include #include #include #define creator "RKK" using namespace std; int factorial(int n) { return (n == 0 || n == 1) ? 1 : n * factorial(n - 1); } int fibonacci(int n) { return (n == 0 || n == 1) ? n : fibonacci(n - 1) + fibonacci(n - 2); } bool even(int n = 2) { if (n > 30) return false; if (n != 0 && n % 2 == 0) cout << n << " "; return even(n + 1); } int sumofdigit(int n) { return (n%10==0) ? 0 : (n % 10) + sumofdigit(n / 10); } bool prime(int n, int d = 2) { if (n == 2) return true; if (d*d > n) return true; if (n%d == 0) return false; return prime(n, d + 1); } // prefered one bool prime1(int n, int d) { return (d == 1)? 1:((n%d == 0)?0:prime1(n, d - 1)) ; } int gcd(int a, int b) { return (a%b == 0) ? b : gcd(b, a%b); } bool factor(int n, int a = 1) { if (a > 30) return false; if (n%a == 0) cout << a << " "; return factor(n, a + 1); } string strReverse(string str, int len) { string s = "", temp = str; if (len <= 0) return s; if (len > 0) { s += temp[len - 1]; cout << s; } return strReverse(str, len - 1); } int armstrong(int n, int len) { int temp = n; return (temp % 10 == 0) ? 0 : pow(temp % 10, len) + armstrong(temp / 10, len); } int palindrome(int n, int rev = 0) { int temp = n, t = (rev * 10)+temp % 10; return (temp / 10 == 0) ? t : palindrome(temp / 10, t); } int main(void) { cout << "Factorial of 5: " << factorial(5) << "\n\n"; cout << "Fibonacci Series: "; for (int i = 0; i < 10; i++) cout << fibonacci(i) << " "; cout << "\n\n"; cout << "Even Nos: "; even(); cout << "\n\n"; cout << "Sum of 12345: " << sumofdigit(12345) << "\n\n"; cout << "Prime nos: "; for (int i = 2; i < 30; i++) if (prime(i) == true) cout << i << " "; cout << "\n\n"; cout << "Prime(2) nos: "; for (int i = 2; i < 30; i++) if (prime1(i,i/2) == true) cout << i << " "; cout << "\n\n"; cout << "gcd(54,24) = " << gcd(54, 24) << "\n\n"; cout << "Factors of 28: "; factor(28); cout << "\n\n"; char name[] = creator; cout << "reverse(\"" << name << "\") = \""; cout << strReverse(name, (sizeof(name) / sizeof(*name)) - 1) << "\"" << "\n\n"; string no = "1634"; if(armstrong(atoi(no.c_str()), no.length()) == (atoi(no.c_str()))) cout << no << " is an Armstrong number." << "\n\n"; else cout << no << " is not an Armstrong number." << "\n\n"; int num = 12321; if (palindrome(num) == num) cout << num << " is Palindrome." << "\n\n"; else cout << num << " is not Palindrome." << "\n\n"; }

Recursion examples