What does a zero value for a slice mean in a programming language?

In Go language, a slice is a dynamic array that contains a reference to an array, along with its length and capacity.

The zero value of a slice is nil. Such a slice does not point to any array, and its length and capacity are zero.

Features of a zero slice:

• It can be checked with slice == nil.
• Attempting to access elements of such a slice will cause a panic.
• It can be used as an empty slice, for example, to indicate the absence of data.

Example:

var s []int // s == nil
fmt.Println(s == nil) // true
fmt.Println(len(s))   // 0
fmt.Println(cap(s))   // 0

// You can safely initialize an empty slice:
s = []int{}
fmt.Println(s == nil) // false
fmt.Println(len(s))   // 0

Thus, the zero value of a slice is nil, which is different from an empty but non-nil slice.