Go中的指针运算

Question

考虑到您可以（想不出一个很好的表达方式，但是）在 Go 中操作指针，是否可以像在 C 中那样执行指针运算，比如遍历数组？我知道现在循环对于这类事情来说很好，但我只是好奇它是否可能。

Answer 1

没有。来自 Go FAQ:

Why is there no pointer arithmetic?

Safety. Without pointer arithmetic it's possible to create a language that can never derive an illegal address that succeeds incorrectly. Compiler and hardware technology have advanced to the point where a loop using array indices can be as efficient as a loop using pointer arithmetic. Also, the lack of pointer arithmetic can simplify the implementation of the garbage collector.

也就是说，您可以使用 unsafe 包来解决这个问题，但是 只是不要 :

package main

import "fmt"
import "unsafe"

func main() {
    vals := []int{10, 20, 30, 40}
    start := unsafe.Pointer(&vals[0])
    size := unsafe.Sizeof(int(0))
    for i := 0; i < len(vals); i++ {
        item := *(*int)(unsafe.Pointer(uintptr(start) + size*uintptr(i)))
        fmt.Println(item)
    }
}

https://play.golang.org/p/QCHEQqy6Lg

Answer 2

从 Go 1.17 开始，我们现在有了 unsafe.Add，这让事情变得更容易了：

package main

import (
    "unsafe"
)

func main() {
    vals := []int{10, 20, 30, 40}

    ptrStart := unsafe.Pointer(&vals[0])
    itemSize := unsafe.Sizeof(vals[0])

    for i := 0; i < len(vals); i++ {
        item := *(*int)(unsafe.Add(ptrStart, uintptr(i)*itemSize))
        println(item)
    }
}

Playground.

Go中的指针运算

Pointer arithmetic in Go

pointers

go

pointer-arithmetic

Why is there no pointer arithmetic?