pointers - 如何为指针参数分配地址

Question

我正在尝试编写一个接受 struct 指针并将其指向另一个地址的函数。

我知道我可以简单地编写一个函数，它接受一个指针并像这样操作 struct 字段:

func ManipulateStruct(myPointer *MyStruct) {
    myPointer.Field1 = "new value"
    myPointer.Field2 = 10
}

但是，是否可以这样写:

func ManipulateStruct(myPointer *MyStruct) {
    newPointer := new(MyStruct)
    newPointer.Field1 = "new value"
    newPointer.Field2 = 10

    // myPointer = &newPointer <-- illegal
    // cannot use &newPointer (type **MyStruct) as type *MyStruct in assignment

    myPointer = newPointer
}

Answer 1

使用 new 生成指向您的 struct 的指针，因此您需要像 this 这样的指针:

package main

import "fmt"

func main() {
    var ptr *MyStruct
    ManipulateStruct(&ptr)
    fmt.Println(ptr)
}
func ManipulateStruct(myPointer **MyStruct) {
    newPointer := new(MyStruct)
    newPointer.Field1 = "new value"
    newPointer.Field2 = 10
    *myPointer = newPointer
}

type MyStruct struct {
    Field1 string
    Field2 int
}

输出:

&{new value 10}