CODEWITHSUNDEEP
goslicememory-address
user
user

Reputation: 2884

How to print the memory address of a slice in Golang?

I have some experience in C and I am totally new to golang.

func learnArraySlice() {
  intarr := [5]int{12, 34, 55, 66, 43}
  slice := intarr[:]
  fmt.Printf("the len is %d and cap is %d \n", len(slice), cap(slice))
  fmt.Printf("address of slice 0x%x add of Arr 0x%x \n", &slice, &intarr)
}

Now in golang slice is a reference of array which contains the pointer to an array len of slice and cap of slice but this slice will also be allocated in memory and i want to print the address of that memory. But unable to do that.

Upvotes: 33

Views: 43738

Answers (4)

AllenPu
AllenPu

Reputation: 11

package main

import (
    "fmt"
    "reflect"
    "unsafe"
)

func main() {
    intArr := [5]int{1, 2, 3, 4, 5}
    intSlice := intArr[:]
    fmt.Printf("slice addr= %p, len= %d, cap= %d\n", &intSlice, len(intArr), cap(intArr))
    fmt.Printf("array addr= %p, len= %d, cap= %d\n", &intArr, len(intArr), cap(intArr))
    fmt.Printf("slice first elem addr=%p\n", &intSlice[0])
    fmt.Printf("backend array of slice addr=%p\n", intSlice)
    fmt.Printf("backend array of slice addr=%#v\n", *((*reflect.SliceHeader)(unsafe.Pointer(&intSlice))))
}

output:

slice addr= 0xc0000a4018, len= 5, cap= 5
array addr= 0xc0000b6000, len= 5, cap= 5
slice first elem addr=0xc0000b6000
backend array of slice addr=0xc0000b6000
backend array of slice addr=reflect.SliceHeader{Data:0xc0000b6000, Len:5, Cap:5}

Upvotes: 1

Volker
Volker

Reputation: 42413

Slices and their elements are addressable:

s := make([]int, 10)
fmt.Printf("Addr of first element: %p\n", &s[0])
fmt.Printf("Addr of slice itself:  %p\n", &s)

Upvotes: 18

peterSO
peterSO

Reputation: 166569

For the addresses of the slice underlying array and the array (they are the same in your example),

package main

import "fmt"

func main() {
    intarr := [5]int{12, 34, 55, 66, 43}
    slice := intarr[:]
    fmt.Printf("the len is %d and cap is %d \n", len(slice), cap(slice))
    fmt.Printf("address of slice %p add of Arr %p\n", &slice[0], &intarr)
}

Output:

the len is 5 and cap is 5 
address of slice 0x1052f2c0 add of Arr 0x1052f2c0

Upvotes: 5

seong
seong

Reputation: 1996

http://golang.org/pkg/fmt/

fmt.Printf("address of slice %p add of Arr %p \n", &slice, &intarr)

%p will print the address.

Upvotes: 53

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