This article will describe different ways of knowing the type of an object in Go

Using Reflect Package

Reflect package provides some useful inspect functions that let us know the type

package main

import (
    "fmt"
    "reflect"
)

func main() {
    var test interface{}
    test = "test_string"
    fmt.Println(reflect.TypeOf(test))
}

Output:

string

Using Type Assertion

package main

import "fmt"

func main() {
    var test interface{}
    test = "test_string"
    val, ok := test.(string)
    if ok {
        fmt.Printf("Test is of type string with value %s\n", val)
    } else {
        fmt.Printf("Unknown Type %T", test)
    }
    test = 2
    val2, ok := test.(int)
    if ok {
        fmt.Printf("Test is of type int with value %d\n", val2)
    } else {
        fmt.Printf("Unknown Type %T", test)
    }
}

Output:

Test is of type string with value test_string
Test is of type int with value 2

Using Switch

package main

import "fmt"

func main() {
    printType("test_string")
    printType(2)
}

func printType(t interface{}) {
    switch v := t.(type) {
    case string:
        fmt.Println("Type: string")
    case int:
        fmt.Println("Type: int")
    default:
        fmt.Printf("Unknown Type %T", v)
    }
}

Output:

Type: string
Type: int

Using printf or sprintf

package main

import (
    "fmt"
)

func main() {
    var test interface{}
    test = "test_string"
    //Using Sprintf
    testType := fmt.Sprintf("%T", test)
    fmt.Println(testType)
    //Using printf
    fmt.Printf("%T\n", test)
}

Output:

string
string