如何在Go中分配一个浮点数？

Question

I'm learning Go programming and try to test the following average function:

func average(xs []float64) float64 {
    total := 0.0
    for _, v := range xs {
        total += v
    }
    return total / float64(len(xs))
}

I tried to generate a slice of random float numbers by:

var xs []float64
for n := 0; n < 10; n++ {
    xs[n] = rand.Float64()
}

however, I got

panic: runtime error: index out of range

Question:

1. How to generate a slice of random number in Golang?
2. Is expression or function call, like xs := []float64 { for ... } allowed in slice literals?

Answer 1

Your method of generating the random numbers is fine, however xs is empty, and Go doesn't automatically extend slices. You could use append, however since you know the size in advance, it's most efficient to replace

var xs []float64

with

xs := make([]float64, 10)

which will give it the right size initially.