I have the following functions:
func (c *Class)A()[4]byte
func B(x []byte)
I want to call
B(c.A()[:])
but I get this error:
cannot take the address of c.(*Class).A()
How do I properly get a slice of an array returned by a function in Go?
The value of c.A()
, the return value from a method, is not addressable.
Address operators
For an operand x of type T, the address operation &x generates a pointer of type *T to x. The operand must be addressable, that is, either a variable, pointer indirection, or slice indexing operation; or a field selector of an addressable struct operand; or an array indexing operation of an addressable array. As an exception to the addressability requirement, x may also be a composite literal.
Slices
If the sliced operand is a string or slice, the result of the slice operation is a string or slice of the same type. If the sliced operand is an array, it must be addressable and the result of the slice operation is a slice with the same element type as the array.
Make the value of c.A()
, an array, addressable for the slice operation [:]
. For example, assign the value to a variable; a variable is addressable.
For example,
package main
import "fmt"
type Class struct{}
func (c *Class) A() [4]byte { return [4]byte{0, 1, 2, 3} }
func B(x []byte) { fmt.Println("x", x) }
func main() {
var c Class
// B(c.A()[:]) // cannot take the address of c.A()
xa := c.A()
B(xa[:])
}
Output:
x [0 1 2 3]
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