b14_type_inference.go

package basics

import "fmt"

// https://tour.golang.org/basics/14
// Type inference

// When declaring a variable without specifying
// an explicit type (either by using the := syntax
// or var = expression syntax), the variable's type is
// inferred from the value on the right hand side.
//
// When the right hand side of the declaration is typed,
// the new variable is of that same type:
// 	var i int
// 	j := i // j is an int
//
// But when the right hand side contains an untyped
// numeric constant, the new variable may be an int, float64
// or complex128 depending on the precision of the constant:
// 	i := 42           // int
// 	f := 3.142        // float64
// 	g := 0.867 + 0.5i // complex128
//
// Try changing the initial value of v in the example code
// and observe how its type is affected.
func TypeInference() {
	v1 := 42
	fmt.Printf("v1 is of type %T\n", v1)

	v2 := 42.2
	fmt.Printf("v2 is of type %T\n", v2)

	v3 := "42"
	fmt.Printf("v3 is of type %T\n", v3)
}