Sum of "n" Slices values in Golang - for-loop

Question

I am trying to make a simple average calculator in golang using Slices and For Loops.
But i am having an error in VS code, this one:
panic: runtime error: index out of range [0] with length 0
goroutine 1 [running]:
main.main()
C:/Desktop/cs50/week2/myarray.go:16 +0x134
exit status 2
I am using VS code on W10.
My code:
package main
import "fmt"
func main() {
var n int
scores := []uint{}
var sumScores float32 = 0
fmt.Println("How many scores?") //ask user how many values
fmt.Scan(&n) //get how many values
for i := 0; i < n; i++ {
fmt.Printf("Scores: ") // ask for values
fmt.Scan(&scores[i]) // get values
sumScores = sumScores + float32(scores[i]) // sum values
}
fmt.Printf("Average: %f\n", sumScores/float32(n)) //average value
}
Any idea what can be wrong?
I think it could be related to my Slice definition using float32.
Thank you in advanced.

Answer 1

This works perfectly, you just have to indicate the slice`s inital size:
func main() {
var n int
var sumScores float32 = 0
fmt.Println("How many scores?") //ask user how many values
fmt.Scan(&n) //get how many values
scores := make([]uint, n, n)
for i := 0; i < n; i++ {
fmt.Printf("Scores: ") // ask for values
fmt.Scan(&scores[i]) // get values
sumScores = sumScores + float32(scores[i]) // sum values
}
fmt.Printf("Average: %f\n", sumScores/float32(n)) //average value
}
for the learning purposes
The way you've declared the scores slice, it's just an empty slice so you can append to it first and then scan the number in newly generated position. (but this is certainly not the way for this specific problem)
func main() {
var n int
scores := []uint{}
var sumScores float32 = 0
fmt.Println("How many scores?") //ask user how many values
fmt.Scan(&n) //get how many values
for i := 0; i < n; i++ {
fmt.Printf("Scores: ") // ask for values
scores = append(scores, 0)
fmt.Scan(&scores[i]) // get values
sumScores = sumScores + float32(scores[i]) // sum values
}
fmt.Printf("Average: %f\n", sumScores/float32(n)) //average value
}

Answer 2

scores := []uint{}
This is a slice literal, you should use Golang built-in function append with it.
Like #no0ob's second example does, or this:
func main() {
var n int
var tmpVal uint
scores := []uint{}
var sumScores float32 = 0
fmt.Println("How many scores?") //ask user how many values
fmt.Scan(&n) //get how many values
for i := 0; i < n; i++ {
fmt.Printf("Scores: ") // ask for values
fmt.Scan(&tmpVal) // save input to tmpVal
scores = append(scores, tmpVal) // append tmpVal to scores
sumScores = sumScores + float32(scores[i]) // sum values
}
fmt.Printf("Average: %f\n", sumScores/float32(n)) //average value
}