Question

I want to calculate the power of 2 using recursion. Here is my code:

class Aufg1{
    public static void main(String args[]){
        int erg = zweiHochPositiv(10);
    }

    public static int zweiHochPositiv(int exponent){
        if(exponent > 0)
            return (2*zweiHochPositiv(exponent--));
        else
            return 1;
    }
}

I get a lot of errors at

return (2*zweiHochPositiv(exponent--));

but I have no idea what may be wrong.

Answer 1

Replace

return (2*zweiHochPositiv(exponent--));

with

return (2*zweiHochPositiv(exponent - 1));

exponent-- evaluates to the value of the exponent variable and then decrements it. So when you call zweiHochPositiv(1), the method will call zweiHochPositiv(1) again.

As a result, this method, when called with a value > 0, will recurse indefinitely and ultimately overflow the stack.