[SOLVED] Multiply two numbers through recurssion

Issue

 #include<iostream>
using namespace std;
int multiply (int num1, int num2){

if (num1 > 0)

  return num2 + multiply(num1-1,num2);


}

int main(){

int mult = multiply(5,6);
cout<<mult;
}

I am trying to multiply two numbers through recurssion, but i am not getting the desired result, i want to print 30 but it is given me 36, i am unable to dry run it and make it’s tree diagram

Solution

You are invoking undefined behavior by letting the execution reach at end of function definition without executing return statement in function whose return type is not void.

 #include<iostream>
using namespace std;
int multiply (int num1, int num2){

if (num1 > 0)

  return num2 + multiply(num1-1,num2);

return 0; // add this
}

int main(){

int mult = multiply(5,6);
cout<<mult;
}

Note: indentation looks bad, but I am respecting the original code. Readable:

#include <iostream>

int multiply (int num1, int num2)
{
    if (num1 > 0)
        return num2 + multiply(num1 - 1, num2);
    return 0;
}
    
int main()
{
    std::cout << multiply(5, 6) << '\n';
}

Answered By – MikeCAT

Answer Checked By – Mildred Charles (BugsFixing Admin)