轉到陣列片

Question

我有以下功能：

func (c *Class)A()[4]byte 
func B(x []byte) 

我想打電話給

B(c.A()[:]) 

，但我得到這個錯誤：

cannot take the address of c.(*Class).A() 

我如何在Go中正確地獲取由函數返回的數組的切片？

Answer 1

c.A()的值，來自方法的返回值不可尋址。

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.

使c.A()用於切片操作[:]的值，陣列，可尋址的。例如，將該值分配給一個變量;一個變量是可尋址的。

例如，

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[:]) 
} 

輸出：

x [0 1 2 3] 

Answer 2

你有沒有試過先在本地變量中粘貼數組？

ary := c.A() 
B(ary[:])