go - Why Golang cannot generate json from struct with front lowercase character?

Question

I am trying to print json result from struct I created as following:

type Machine struct {
  m_ip string
  m_type string
  m_serial string
}

and print out

m:= &Machine{ m_ip:"test", m_type:"test", m_serial:"test" }
m_json:= json.Marshal(m)
fmt.Println(m_json)

However, result returned just {}

Secondly,I tried to changed the first letter of words to Uppercase as follow:

type Machine struct{
  MachIp string
  MachType string
  MachSerial string
}

and it works! Why doesn't the word with lowercase character at the front work, anyway?

Answer 1

Waitting for answers