Unexpected outcome of while loop? - go

Question

I've just started learning Golang, so I set myself a challenge to order a slice of integers in highest to lowest and/or lowest to highest. I've got most of it right, but it seems to miss out the last item?
Expected: [5, 4, 1]
Got: [5, 4]
Now, this line is the issue,
for len(rebuiltNumbers) < len(numbers)
If I change it to this, it works fine:
for len(rebuiltNumbers) < len(numbers) + 2
but I don't understand why? Does while or for form of while work differently in go?
Here is the full code
package main
import "fmt"
func main() {
var numbers = []int { 1, 4, 5 }
fmt.Println(orderArrayOfNumbers(numbers, true))
}
func orderArrayOfNumbers(numbers []int, descending bool) []int {
var rebuiltNumbers []int
for len(rebuiltNumbers) < len(numbers) + 1 {
var next = 0
if descending {
next = getHighestItemInArray(numbers);
} else {
next = getLowestItemInArray(numbers);
}
rebuiltNumbers = append(rebuiltNumbers, next)
numbers = remove(numbers, next)
}
return rebuiltNumbers
}
func getHighestItemInArray(numbers []int) int {
var highest = 0
var hasSet = 0
for i := 0; i < len(numbers); i++ {
if numbers[i] > highest || hasSet == 0 {
highest = numbers[i]
hasSet = 1
}
}
return highest
}
func getLowestItemInArray(numbers []int) int {
var lowest = 0
var hasSet = 0
for i := 0; i < len(numbers); i++ {
if numbers[i] < lowest || hasSet == 0 {
lowest = numbers[i]
hasSet = 1
}
}
return lowest
}
func remove(slice []int, remove int) []int {
var rebuiltSlice = []int {}
for i := 0; i < len(slice); i++ {
if slice[i] != remove {
rebuiltSlice = append(rebuiltSlice, slice[i])
}
}
return rebuiltSlice
}

Answer 1

These two lines are important
rebuiltNumbers = append(rebuiltNumbers, next)
numbers = remove(numbers, next)
When you append to one array and remove from the other, the sizes will meet eventually in the middle. So you should rather save the size upfront, and then compare to that, e.g.
var nOrig = len(numbers)
for len(rebuiltNumbers) < nOrig {
// ...
}