恐慌：运行时错误：索引超出范围，但数组长度不为null

Question

i am having a hard time learning how to loop through a string in Golang to do some stuff(separate words than contain vowels).

I wrote this code snippet https://play.golang.org/p/zgDtOyq6qf Here is the error :

panic: runtime error: index out of range

goroutine 1 [running]:
panic(0x1045a0, 0x1040a010)
    /usr/local/go/src/runtime/panic.go:500 +0x720
main.myFunc(0x114130, 0x4, 0x0, 0x0, 0x0, 0x3ba3)
    /tmp/sandbox960520145/main.go:19 +0x1a0
main.main()
    /tmp/sandbox960520145/main.go:10 +0x40

I searched in this forum and someone said that it's due to the length of the array but it's not the case here. Ican't figure out how to solve this. Can someone please suggest anything? Thanks

Answer 1

The issue is that you are creating a slice with length 0, but with a maximum capacity of 4, but at the same time you are trying to allocate already a value to the zeroth index of the slice created, which is normally empty. This is why you are receiving the index out of range error.

result := make([]string, 0, 4)
fmt.Println(len(result)) //panic: runtime error: index out of range

You can change this code with:

result := make([]string, 4)

which means the capacity will be the same length as the slice length.

fmt.Println(cap(result)) // 4
fmt.Println(len(result)) // 4

You can read about arrays, slices and maps here: https://blog.golang.org/go-slices-usage-and-internals