Loops without for keyword

Golang Challenge

package main

import (
	"bufio"
	"fmt" // A package in the Go standard library.
	"os"
	"strconv"
	"strings"
)

//global vars
var casenum int
var testnum int
var i = 0        //iterator for each case
var j = 0        //iterator for case's number
var sum int = 0  //sum of a case
var result []int //result array

func main() {
	readcasenum()
	gotocase(casenum)
	printresult()
}

func readcasenum() {
	fmt.Scan(&casenum)
	if casenum > 100 || casenum < 1 {
		fmt.Print("the first line of the input will be an integer N (1 <= N <= 100)")
		os.Exit(0)
	}

}

//go into each test case
func gotocase(casenumber int) {
	if j < casenumber {
		j++
		i = 0
		sum = 0
		runtest()
		gotocase(casenum)
	} else {
		j = 0
		return
	}
}

//run test for each case
func runtest() {
	testnum = 0
	fmt.Scan(&testnum)
	if testnum < 0 || testnum > 100 {
		fmt.Print("test cases consists of one line containing an integer X (0 < X <= 100)")
		os.Exit(0)
	}
	scanner := bufio.NewScanner(os.Stdin)
	scanner.Scan()
	scanner.Text()
	var test = scanner.Text()
	input := strings.Split(test, " ")
	//when X==0, skip the conversion
	if testnum != 0 {
		convert(input)
	}
	result = append(result, sum)
}

//calculate each test case's sum of squares
func convert(strarray []string) {
	var ctstr int //convert the string array into integers
	ctstr, err := strconv.Atoi(strarray[i])
	if ctstr < -100 || ctstr > 100 {
		fmt.Print("integers should be: (Yn, -100 <= Yn <= 100)")
		os.Exit(0)
	}
	//calculate the sum of squares of the integers excepting negatives
	if ctstr > 0 {
		sum += ctstr * ctstr //return the square value if it's not negative
	}
	i++
	if err != nil {
		panic(err)
	}

	if i < testnum {
		convert(strarray)
	} else {
		return
	}
}

func printresult() {
	if j < casenum {
		if j+1 == casenum {
			//no newline if it's the last number
			fmt.Fprintf(os.Stdout, "%d", result[j])
		} else {
			fmt.Fprintf(os.Stdout, "%d\n", result[j])
		}
		j++
		printresult()
	} else {
		return
	}

}