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

User · Answer

To get the type of fields in struct   package main  import      fmt     reflect     type testObject struct     Name   string   Age    int   Height float64    func main        tstObj    testObject Name   yog prakash   Age  24  Height  5 6     val    reflect ValueOf  amp tstObj  Elem      typeOfTstObj    val Type      for i    0  i  lt  val NumField    i            fieldType    val Field i         fmt Printf  object field  d key  s value  v type  s  n             i  typeOfTstObj Field i  Name  fieldType Interface              fieldType Type             Output  object field 0 key Name value yog prakash type string  object field 1 key Age value 24 type int  object field 2 key Height value 5 6 type float64   See in IDE https   play golang org p bwIpYnBQiE

User · Answer

To be short  please use fmt Printf   T   var1   or its other variants in the fmt package

User · Answer

You can check the type of any variable instance at runtime either using the  reflect  packages TypeOf function or by using fmt Printf     package main  import       fmt      reflect     func main         value1     Have a Good Day      value2    50     value3    50 78      fmt Println reflect TypeOf value1        fmt Println reflect TypeOf value2       fmt Println reflect TypeOf value3       fmt Printf   T  value1      fmt Printf   T  value2      fmt Printf   T  value3

User · Answer

you can use reflect TypeOf    basic type e g   int  string   it will return its name  e g   int  string   struct  it will return something in the format  lt package name gt   lt struct name gt   e g   main test

User · Answer

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

User · Answer

You can just use the fmt package fmt Printf   method  more information  https   golang org pkg fmt   example  https   play golang org p aJG5MOxjBJD

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To get a string representation   From http   golang org pkg fmt       T    a Go-syntax representation of the type of the value   package main import  fmt  func main        types      interface     a  6 6 0 true      for   v    range types          fmt Printf   T n  v            Outputs   string int float64 bool

User · Answer

You can use  interface     type  as in this playground  package main import  fmt  func main        types      interface     a  6 6 0 true      for   v    range types          fmt Printf   T n  v          switch v  type            case int             fmt Printf  Twice  v is  v n   v  v  int    2          case string             fmt Printf   q is  v bytes long n   v  len v  string           default            fmt Printf  I don t know about type  T  n   v

User · Answer

reflect package comes to rescue   reflect TypeOf obj  String     Check this demo

User · Answer

If we have this variables   var counter int   5 var message string     Hello  var factor float32   4 2 var enabled bool   false      1  fmt Printf  T format   to use this feature you should import  fmt     fmt Printf   T  n  factor        factor type  float32      2  reflect TypeOf function   to use this feature you should import  reflect     fmt Println reflect TypeOf enabled      enabled type   bool      3  reflect ValueOf X  Kind     to use this feature you should import  reflect      fmt Println reflect ValueOf counter  Kind       counter type   int

User · Answer

Use the reflect package      Package reflect implements run-time reflection  allowing a program to   manipulate objects with arbitrary types  The typical use is to take a   value with static type interface   and extract its dynamic type   information by calling TypeOf  which returns a Type    package main  import        fmt       reflect     func main         b    true     s           n    1     f    1 0     a      string  foo    bar    baz        fmt Println reflect TypeOf b       fmt Println reflect TypeOf s       fmt Println reflect TypeOf n       fmt Println reflect TypeOf f       fmt Println reflect TypeOf a       Produces   bool string int float64   string   Playground  Example using ValueOf i interface    Kind     package main  import        fmt       reflect     func main         b    true     s           n    1     f    1 0     a      string  foo    bar    baz        fmt Println reflect ValueOf b  Kind        fmt Println reflect ValueOf s  Kind        fmt Println reflect ValueOf n  Kind        fmt Println reflect ValueOf f  Kind        fmt Println reflect ValueOf a  Index 0  Kind       For slices and strings     Produces   bool string int float64 string   Playground

User · Answer

I would stay away from the reflect      package  Instead use  T  package main  import        fmt     func main         b    true     s           n    1     f    1 0     a      string  foo    bar    baz        fmt Printf   T n   b      fmt Printf   T n   s      fmt Printf   T n   n      fmt Printf   T n   f      fmt Printf   T n   a

User · Answer

Best way is using reflection concept in Google  reflect TypeOf gives type along with the package name reflect TypeOf   Kind   gives underlining type

User · Answer

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

[go] How to find the type of an object in Go?

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