Recursion

[scu1casper]

Can anyone explain how to do the calculation I have below using recursion??

int RecursiveEvenSum (int num, int &finalRecursiveSum)
{
    // will compute and return the same sum using recursion
    for (int i = 0; i <= num; i += 2)
    finalRecursiveSum += i;
}

Should be calculating the sum of all EVEN integers from 1 to num (inclusive)

[vlad from moscow]

As I showed in other thread the function can look the following way

int LoopEvenSum ( int num )
{
    return ( ( num > 1 ) ? 2 + LoopEvenSum ( num - 2 ) : 0 );
}

another way is

void RecursiveEvenSum (int num, int &finalRecursiveSum)
{
    // will compute and return the same sum using recursion.
    if (num < 2)
    {
        finalRecursiveSum = 0;
    }
    
    else
    {
        RecursiveEvenSum (num - 2, finalRecursiveSum);
        finalRecursiveSum += 2 * ( num / 2 ) ; 
    }
}

[fg109]

Recursion means to have the function keep calling itself until some condition is met. So instead of having a for loop, you would call RecursiveEvenSum again.

You'll probably need to change/overload the function so that it takes 3 arguments.