What Is unsafe.Slice and unsafe.String in Go

unsafe.Slice and unsafe.String are functions in the unsafe package that convert between []byte and string without copying data, bypassing Go's type safety to improve performance. They allow you to treat a byte slice as a string (and vice versa) by reinterpreting the underlying memory, but they require you to ensure the data remains valid and does not escape the scope where it is safe to do so.

import "unsafe"

// Convert []byte to string without copying
b := []byte("hello")
s := unsafe.String(unsafe.SliceData(b), len(b))

// Convert string to []byte without copying
s2 := "world"
b2 := unsafe.Slice(unsafe.StringData(s2), len(s2))

These functions let you switch between text (strings) and raw data (byte slices) instantly without making a duplicate copy of the data in memory. It is like looking at the same stack of papers through a different colored lens instead of photocopying the whole stack. You use this when performance is critical and you are sure the original data won't change unexpectedly.