How can you understand the difference between array and slice two data types in Golang

Codes

package main

import (
    "fmt"
)

func loopSlice(list []int) {
    for _, v := range list {
        fmt.Print(v, " ")
    }
    fmt.Print("\n")
}

func loopArray(list [4]int) {
    for _, v := range list {
        fmt.Print(v, " ")
    }
    fmt.Print("\n")
}

a := []int{2, 3, 4}
b := [4]int{1, 2, 3, 4}

loopSlice(a)
loopArray(b)

2 3 4 
1 2 3 4 

loopArray(a)

repl.go:1:11: cannot use <[]int> as <[4]int> in argument to loopArray

loopSlice(b)

repl.go:1:11: cannot use <[4]int> as <[]int> in argument to loopSlice

Conclusion 

So the array in golang is length fixed. If you want to use it. You have to clearly specify the length of that array.

Meanwhile, the slice is different, you don’t have to specify the length of it.

Again:

  • array: var a [5]int
  • slice: var b []int
​