package main


import "fmt"

func binarySearch(slice []int, guess int) (err error) {
	firstValue := slice[0]
	lastValue := len(slice) - 1

	for firstValue <= lastValue {
		mid := (firstValue + lastValue) / 2
		trying := slice[mid]
		if trying == guess {
			fmt.Println(mid)
			break
		} else if trying > guess {
			lastValue = mid - 1
		} else if trying < guess {
			firstValue = mid + 1
		}
	}
	return err
}


func main() {
	var intSlice = []int{1, 2, 3, 4}
	binarySearch(intSlice, 2)
}