使用Golang中的递归的数组中的平方和

Question

So my friend gave me this task where the sum of squares of positive numbers must be calculated using recursion.
Conditions - The input will be a string with space separated numbers
This is what I've come so far but this shows a runtime error.

Here is the full error https://ideone.com/53oOjN

package main
import(
    'fmt',
    'strings',
    'strconv'
)
var n int = 4
var sum_of_squares int = 0
func sumOfSquares(strArray []string, iterate int) int{
    number, _ := strconv.Atoi(strArray[iterate])
    if number > 0 {
        sum_of_squares += number*number
    }
    if iterate == n {
        return 0 // just to end the recursion
    }
    return sumOfSquares(strArray, iterate+1)
}
func main() {
    str := "1 2 3 4"
    strArray := strings.Fields(str)
    result := sumOfSquares(strArray, 0)
    fmt.Println(sum_of_squares, result)
}

Answer 1

The rule of thumb in recursion is termination condition. It should exist and it should exist in the right place.

func sumOfSquares(strArray []string, iterate int) int{
    if iterate >= len(strArray) { 
        return sum_of_squares
    }
    number, _ := strconv.Atoi(strArray[iterate]) //TODO: handle err here
    sum_of_squares += number*number

    return sumOfSquares(strArray, iterate+1)
}

---

Just for you information: canonical recursion should not save it's state into global fields. I would suggest using following function signature.

func sumOfSquares(strArray []string, iterate, currentSum int) int{
    //...    
    return sumOfSquares(strArray, iterate+1, sum_of_squares)
}

So that you don't need to store sum_of_squares somewhere. You will just pass it to next function invocation.