Question

I has encountered an error while implement the below code:

package main

import (
    "fmt" 
)

type Struct struct {
    a int
    b int
}

func Modifier(ptr *Struct, ptrInt *int) int {
    *ptr.a++
    *ptr.b++
    *ptrInt++
    return *ptr.a + *ptr.b + *ptrInt
}

func main() { 
    structure := new(Struct)
    i := 0         
    fmt.Println(Modifier(structure, &i))
}

That gives me an error something about “invalid indirect of ptr.a (type int)…”. And also why the compiler don’t give me error about ptrInt? Thanks in advance.

Answer 1

Just do

func Modifier(ptr *Struct, ptrInt *int) int {
    ptr.a++
    ptr.b++
    *ptrInt++
    return ptr.a + ptr.b + *ptrInt
}

You were in fact trying to apply ++ on *(ptr.a) and ptr.a is an int, not a pointer to an int.

You could have used (*ptr).a++ but this is not needed as Go automatically solves ptr.a if ptr is a pointer, that’s why you don’t have -> in Go.