Игорь Пашев

/*
 SYNOPSIS:

 With GCC >= 4.6:
 # gccgo gcd.go -o gcd-go
 # ./gcd-go 11 22 33 44 121

 With Google Go (6g for amd64, 8g for x86):
 # 6g -o gcd-go.o  gcd.go
 # 6l -o gcd-go-6g gcd-go.o
 # ./gcd-go-6g 11 22 33 44 121

 GCC makes dynamically linked binary,
 but Google Go - statically linked

*/

package main

// Both Google Go and GCC issue an error "imported and not used",
// if imported and not used :-)
import "fmt"
import "flag"
import "strconv"

func gcd2 (a, b uint) uint {
    if b == 0 {
        return a
    }
    /* 6g issues an error "function ends without a return statement",
       if we use if ... {... return} else {... return}.
       But GCC doesn't.
    */
    return gcd2(b, a % b)
}

func gcdn (ns []uint) uint {
    var r uint // zero by default
    for i := range ns {
        r = gcd2(r, ns[i])
    }
    return r
}

func main() {
    flag.Parse() // without this 6g will give flag.NArg() = 0 next (WTF?)
    n := flag.NArg()
    if n > 0 {
        ns := make([]uint, n) // We have garbage collector!

        // Or: for i := range ns, since range of ns is equal to flag.NArg()
        for i := 0; i < n; i++ {
            // Drop the second return value (error code):
            ns[i], _ = strconv.Atoui(flag.Arg(i))
        }

        g  := gcdn(ns)
        fmt.Printf("%v\n", g)
    }
}