panic: runtime error: index out of range in Go

Question

I have the following function that takes a command from terminal and prints something based on input. It seems simple enough, if the user types 'add' the system prints a line, if the user types nothing, it prints something else.

Whenever the user types add, it works. If the user doesn't type anything it throws

panic: runtime error: index out of range in GoLang

Why is this?

  func bootstrapCmd(c *commander.Command, inp []string) error {        if inp[0] == "add" {                   fmt.Println("you typed add")               } else if inp[0] == "" {                   fmt.Println("you didn't type add")               }             return nil      } 

Answer 1

If the user does not provide any input, the inp array is empty. This means that even the index 0 is out of range, i.e. inp[0] can't be accessed.

You can check the length of inp with len(inp) before checking inp[0] == "add". Something like this might do:

if len(inp) == 0 {     fmt.Println("you didn't type add") } else if inp[0] == "add" {     fmt.Println("you typed add") }