How to find the type of an object in Go?

Question

How do I find the type of an object in Go? In Python, I just use typeof to fetch the type of object. Similarly in Go, is there a way to implement the same ?

Here is the container from which I am iterating:

for e := dlist.Front(); e != nil; e = e.Next() {     lines := e.Value     fmt.Printf(reflect.TypeOf(lines)) } 

I am not able to get the type of the object lines in this case which is an array of strings.

Answer 1

The Go reflection package has methods for inspecting the type of variables.

The following snippet will print out the reflection type of a string, integer and float.

package main  import (     "fmt"     "reflect" )  func main() {      tst := "string"     tst2 := 10     tst3 := 1.2      fmt.Println(reflect.TypeOf(tst))     fmt.Println(reflect.TypeOf(tst2))     fmt.Println(reflect.TypeOf(tst3))  } 

Output:

Hello, playground string int float64 

see: http://play.golang.org/p/XQMcUVsOja to view it in action.

More documentation here: http://golang.org/pkg/reflect/#Type

Answer 2

I found 3 ways to return a variable's type at runtime:

Using string formatting

func typeof(v interface{}) string {     return fmt.Sprintf("%T", v) } 

Using reflect package

func typeof(v interface{}) string {     return reflect.TypeOf(v).String() } 

Using type assertions

func typeof(v interface{}) string {     switch v.(type) {     case int:         return "int"     case float64:         return "float64"     //... etc     default:         return "unknown"     } } 

Every method has a different best use case:

• string formatting - short and low footprint (not necessary to import reflect package)

• reflect package - when need more details about the type we have access to the full reflection capabilities

• type assertions - allows grouping types, for example recognize all int32, int64, uint32, uint64 types as "int"