Pointer in golang [duplicate]

Question

I am using golang to parse a json string:

str:="{...}"
var f interface{}
json.Unmarshal([]byte(str), f)

fmt.Println(f)

While I got nil in the console.

When I change the code to :

json.Unmarshal([]byte(str), &f)

It will print the json string.

What's going on?

I think research doesn't help always. Sometimes you can't find answer if you don't know correct question. I also think who has 10.6k reputation, didn't come here for upvote. — Shahriar
– Shahriar, Commented Jan 28, 2018 at 11:58

mu is too short · Accepted Answer · 2018-01-28 04:12:34Z

4

Two things are happening:

You didn't read the documentation.
You didn't check json.Unmarshal's return value to check for errors.

From the fine manual:

func Unmarshal(data []byte, v interface{}) error
Unmarshal parses the JSON-encoded data and stores the result in the value pointed to by v. If v is nil or not a pointer, Unmarshal returns an InvalidUnmarshalError.

Unmarshal takes an interface{} because it can unmarshal into all sorts of things (slices, maps, structs, ...) as noted in the documentation.

answered Jan 28, 2018 at 4:12

mu is too short

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