Go Empty Slice Initialization: `make([]int, 0)` vs. `[]int{}` vs. `nil` – Which is Best?

Empty Slice Initialization: Evaluating Two Approaches

To initialize an empty slice with non-fixed size, two common methods are employed:

mySlice1 := make([]int, 0)
mySlice2 := []int{}

Exploring the differences between these approaches is crucial for optimizing code performance and understanding memory management in Go.

Runtime Implications

make([]int, 0) explicitly calls the runtime function runtime.makeslice internally (Go 1.16). This involves allocating memory for the slice header and backing array, even though it initializes the slice's length to zero. It also sets the slice's capacity to the allocated size.

Nil Slice: A Third Option

Another alternative is to create a nil slice:

var mySlice []int

A nil slice is equivalent to a zero-length slice in functionality. However, it does not point to any underlying data.

JSON Marshaling Considerations

It's noteworthy that a nil slice and an empty slice have different behaviors when JSON-marshaled. A nil slice marshals into "null," while an empty slice marshals into "[]".

Memory Allocation

Neither of the mentioned methods, make([]int, 0), []int{}, or creating a nil slice, causes memory allocation.

Recommended Approach

Ultimately, the choice of which approach to use depends on specific requirements and preferences. Consider the following:

• Performance: If optimizing for runtime performance is a priority, using make([]int, 0) may be more efficient.
• Memory Allocation: When minimizing memory allocation is crucial, a nil slice is the best option.
• JSON Marshaling: If JSON marshaling behavior is important, consider the desired output and use make([]int, 0) or []int{} accordingly.

The above is the detailed content of Go Empty Slice Initialization: `make([]int, 0)` vs. `[]int{}` vs. `nil` – Which is Best?. For more information, please follow other related articles on the PHP Chinese website!