reflect.UnsafeAddr() Function in Golang with Examples

Go language provides inbuilt support implementation of run-time reflection and allowing a program to manipulate objects with arbitrary types with the help of reflect package. The reflect.UnsafeAddr() Function in Golang is used to get the pointer to v’s data. To access this function, one needs to imports the reflect package in the program.

Syntax:

func (v Value) UnsafeAddr() uintptr

Parameters: This function does not accept any parameter.
Return Value: This function returns the pointer to v’s data.  

Below examples illustrate the use of the above method in Golang:
Example 1:

C

// Golang program to illustrate
// reflect.UnsafeAddr() Function

package main

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

// Main function
func main() {
        var s = struct{ foo int }{42}
    var i int

    rs := reflect.ValueOf(&s).Elem()
    rf := rs.Field(0)
    ri := reflect.ValueOf(&i).Elem()

    rf = reflect.NewAt(rf.Type(), unsafe.Pointer(rf.UnsafeAddr())).Elem()
    ri.Set(rf)
    rf.Set(ri)
    fmt.Println(rf)
    fmt.Println(ri)

}

Output:

42
42

Example 2:

C

// Golang program to illustrate
// reflect.UnsafeAddr() Function

package main

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

// Main function
func main() {
    var s = struct{ foo int }{374}
    var i int

    rs := reflect.ValueOf(s)

    rf := rs.Field(0)

    rs2 := reflect.New(rs.Type()).Elem()
    rs2.Set(rs)
    rf = rs2.Field(0)
    rf = reflect.NewAt(rf.Type(), unsafe.Pointer(rf.UnsafeAddr())).Elem()

    ri := reflect.ValueOf(&i).Elem() // i, but writable
    ri.Set(rf)

    fmt.Println(rf)
    fmt.Println(ri)

}

Output:

374
374