Infinite loop in Go - for-loop

Question

I want to have the "for loop" to loop 3 times or until the user inputs something other than an integer. Below is my code, although this runs an infinite amount of times and prints out the first value the user enters.
package main
import "fmt"
import "bufio"
import "strconv"
import "os"
import "sort"
func main(){
emptySlice := make([]int, 3) // Capacity of 3
fmt.Println(cap(emptySlice))
scanner := bufio.NewScanner(os.Stdin) // Creating scanner object
fmt.Printf("Please enter a number: ")
scanner.Scan() // Will always scan in a string regardless if its a number
for i := 0; i < cap(emptySlice); i++ { // Should this not run 3 times?
input, err := strconv.ParseInt(scanner.Text(), 10, 16)
if err != nil{
fmt.Println("Not a valid entry! Ending program")
break
}
emptySlice = append(emptySlice, int(input)) // adds input to the slice
sort.Ints(emptySlice) // sorts the slice
fmt.Println(emptySlice) // Prints the slice
}
}

Answer 1

I think there are a couple of minor bugs, but this version should work correctly:
package main
import "fmt"
import "bufio"
import "strconv"
import "os"
import "sort"
func main() {
emptySlice := make([]int, 3) // Capacity of 3
fmt.Println(cap(emptySlice))
scanner := bufio.NewScanner(os.Stdin) // Creating scanner object
for i := 0; i < cap(emptySlice); i++ { // Should this not run 3 times?
fmt.Printf("Please enter a number: ")
scanner.Scan() // Will always scan in a string regardless if its a number
input, err := strconv.ParseInt(scanner.Text(), 10, 16)
if err != nil {
fmt.Println("Not a valid entry! Ending program")
break
}
// emptySlice = append(emptySlice, int(input)) // adds input to the slice
emptySlice[i] = int(input)
}
sort.Ints(emptySlice) // sorts the slice
fmt.Println(emptySlice) // Prints the slice
}
I've moved the prompt into the loop, and I've replaced the append call with a direct assignment to the previously allocated slice entries. Otherwise calling append will just increase the size of the slice.
I've moved the sort and the print outside of the loop, as these seemed to be incorrectly placed too.

Answer 2

The program in the question starts with cap(emptySlice) == 3. Given that each complete iteration of the loop appends a new value to empty slice, we know that cap(emptySlice) >= 3 + i. It follows that the loop does not terminate.
My homework assignment is slightly different: Read up to three integers and print them in sorted order. Here's how I did it:
func main() {
var result []int
scanner := bufio.NewScanner(os.Stdin)
for i := 0; i < 3; i++ {
fmt.Printf("Please enter a number: ")
if !scanner.Scan() {
// Exit on EOF or other errors.
break
}
n, err := strconv.Atoi(scanner.Text())
if err != nil {
// Exit on bad input.
fmt.Println(err)
break
}
result = append(result, n)
}
sort.Ints(result)
fmt.Println(result)
}