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Question

When I'm following this golang blog post about arrays and slices, I tried to pass a pointer to a slice to a function that modify the underlying len property in the slice header:

func PtrSubtractOneFromLength(slicePtr *[]byte) {
    slice := *slicePtr
    *slicePtr = slice[0 : len(slice)-1]
}

And when I tried to refactor it to this from:

func PtrSubtractOneFromLength(slicePtr *[]int) {
    *slicePtr = *slicePtr[0 : len(*slicePtr)-1]
}

I get this error

cannot slice slicePtr (type *[]int)

Where is the magic in the slice := *slicePtr statement?

Answer 1

A slice expression binds stronger than a dereference. Try this:

*slicePtr = (*slicePtr)[0 : len(*slicePtr)-1]