GO language: Reading a file and turning the content into an array

I want to implement this array in main function above but how?

hosts := []string{"inanzzz1@100.79.154.22", "inanzzz2@200.79.190.11"}

Content of JSON file:

inanzzz@inanzzz-VirtualBox:~/go$ go run reader.go < hosts.txt 
{
   {
      "username":"inanzzz1",
      "ip":"100.79.154.22"
   },
   {
      "username":"inanzzz2",
      "ip":"200.79.190.11"
   }
}

GO file which reads the JSON file above:

package main

import (
    "os"
    "bufio"
    "fmt"
)

func main() {
    r := bufio.NewReader(os.Stdin)
    line, err := r.ReadString('\n')
    for i := 1; err == nil; i++ {
        //fmt.Printf("Line %d: %s", i, line)
        fmt.Printf(line)
        line, err = r.ReadString('\n')
    }
}

Assuming that what you have is a json array (first and last {} replaced by []) instead of the invalid JSON described in hosts.txt here you have a working solution:

package main

import (
	"encoding/json"
	"fmt"
	"os"
)

type UsernameIp struct {
	Username string `json:"username"`
	Ip       string `json:"ip"`
}

func main() {
	j := json.NewDecoder(os.Stdin)
	var src []UsernameIp
	j.Decode(&src)

	var hosts []string
	for _, h := range src {
		entry := fmt.Sprintf("%s@%s", h.Username, h.Ip)
		hosts = append(hosts, entry)
	}

	fmt.Println(hosts)
}

Correct hosts.txt file:

[
   {
      "username":"inanzzz1",
      "ip":"100.79.154.22"
   },
   {
      "username":"inanzzz2",
      "ip":"200.79.190.11"
   }
]

You probably should unmarshall json first and then iterate over result.
First - make hosts.txt a valid JSON. For that use [] instead of {}:

[
   {
      "username":"inanzzz1",
      "ip":"100.79.154.22"
   },
   {
      "username":"inanzzz2",
      "ip":"200.79.190.11"
   }
]

Then unmarshall.

Here is full example:

> package main
>
> import (
> "fmt"
> "encoding/json"
> )
>
> func main() {
>
> type host struct {
> Username string
> Ip string
> }
>
> cont := [
> {
> "username":"inanzzz1",
> "ip":"100.79.154.22"
> },
> {
> "username":"inanzzz2",
> "ip":"200.79.190.11"
> }
> ]
>
>
>
> // Read file to some byte array. We will use string for this example.
> var arr []host
> err := json.Unmarshal([]byte(cont), &arr)
> if err != nil {
> fmt.Println(err)
> }
>
> hosts := make([]string, len(arr))
> for i, h := range arr {
> hosts[i] = h.Username + "@" + h.Ip
> }
> fmt.Println(hosts)
> }

You can use ioutil.ReadFile to read the whole file as a string which is a json document and then Unmarshal the string into a struct that you will have made for easy access:

type user_ip struct{
	username string `json:"username"`
	ip string       `json:"ip"`
}

type jsonStruct struct{
	sample []user_ip
}


func main() {

	//you'll have to read file here
    str := `{
			   {
			      "username":"inanzzz1",
			      "ip":"100.79.154.22"
			   },
			   {
			      "username":"inanzzz2",
			      "ip":"200.79.190.11"
			   }
			}`

	userIP := jsonStruct{}

	err := json.Unmarshal(str, &userIP)
	panic(err)

	//do what you want with the struct here
}