golang recursive function how to check return?

Question

Learning golang, proect euler problem 5. I was messing around with a recursive function and I could not figure out a way to get the return value to be correct.

In go I cannot take out the return at the end of the five() function and I also cannot get it to return the right value to execute the if statement in the main() function...

I realize I can do this without the recursion but I would like to know how to do it with recursion if possible.

package main

import (
    "fmt"
    //"os"
)

func recursive(num int, div int) int {

    if div == 1 {
        fmt.Println(num)
        return num
    }
    switch num % div {
    case 0:
        recursive(num, div-1)
    default:
        return -1
    }
    return num
}

func main() {
    for i := 20; ; i += 20 {
        if recursive(i, 19) == 1 {
            fmt.Println("finished")
        }
    }
}

shouldn't that be return recursive(num, div-1)?

Pyonsuke
– Pyonsuke

2016-08-26 03:22:28 +00:00
Commented Aug 26, 2016 at 3:22 — Pyonsuke
– Pyonsuke, Commented Aug 26, 2016 at 3:22
I believe it should also be: if div == 1 { return 1 }

Seva
– Seva

2016-08-26 03:25:49 +00:00
Commented Aug 26, 2016 at 3:25 — Seva
– Seva, Commented Aug 26, 2016 at 3:25

Seva · Accepted Answer · 2016-08-26 03:30:05Z

1

Oh, and besides the comments above, it should also break once the answer is found.

package main

import (
    "fmt"
    //"os" 
)

func recursive(num int, div int) int {
    if div == 1 {
         return 1
    }
    switch num % div {
    case 0:
        return recursive(num, div-1)
    default:
        return -1
    }
    return num
 }

 func main() {
    for i := 120; ; i += 20 {
        if recursive(i, 19) == 1 {
            fmt.Printf ("finished with %v\n", i)
            break;
        }
    }
 }

answered Aug 26, 2016 at 3:30

Seva

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1 Comment

Joff Over a year ago

Yes I was missing the return, I had commented out the os import because I was going to use os.Exit(0).

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