I am having a function like this:

package main
import "flag"
import "fmt"
func print_out_type(x anything) string { switch v := x.(type) { case string: return "A string" case int32: return "An Integer" default: return "A default" }
}
func main() { wordPtr := flag.String("argument1", "foo", "a String") numPtr := flag.Int("argument2", 42, "an Integer") flag.Parse() fmt.Println("word: ", *wordPtr) fmt.Println("number: ", *numPtr)
}

I am trying to return different types of strings based on the type. I am just stuck at the point of how do I write a function that accepts arguments of different types.

2

3 Answers

You can use interface types as arguments, in which case you can call the function with any type that implements the given interface. In Go types automatically implement any interfaces if they have the interface's methods. So if you want to accept all possible types, you can use empty interface (interface{}) since all types implement that. No other modification needs to be done to your function.

func print_out_type(x interface{}) string { switch v := x.(type) { case string: return "A string" case int32: return "An Integer" default: return "A default" }
}

You can also use the reflect package to study the type of an interface variable. For Example:

func print_out_type(x interface{}) string { return reflect.TypeOf(x).String()
}
func main() { fmt.Println(print_out_type(42)) fmt.Println(print_out_type("foo"))
}

Will print

int

string

1

Starting with go 1.18. you can use generics to specify which types can be used in a function.

0

1. First, if you are using a type assertion, you need to check that this operation is successful. eg: value, ok := temp.(int)
2. Second, you can use the interface{} type variable as a parameter to the function. In the Function, you can use type assertion to check the parameter's real type and print out.

2

Your Answer

Sign up or log in

Sign up using Google Sign up using Facebook Sign up using Email and Password Submit

Post as a guest

Post Your Answer Discard

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy