// run // Copyright 2009 The Go Authors. All rights reserved. // Use of this source code is governed by a BSD-style // license that can be found in the LICENSE file. // Test simple type switches on basic types. package main import "fmt" const ( a = iota b c d e ) var x = []int{1, 2, 3} func f(x int, len *byte) { *len = byte(x) } func whatis(x interface{}) string { switch xx := x.(type) { default: return fmt.Sprint("default ", xx) case int, int8, int16, int32: return fmt.Sprint("signed ", xx) case int64: return fmt.Sprint("signed64 ", int64(xx)) case uint, uint8, uint16, uint32: return fmt.Sprint("unsigned ", xx) case uint64: return fmt.Sprint("unsigned64 ", uint64(xx)) case nil: return fmt.Sprint("nil ", xx) } panic("not reached") } func whatis1(x interface{}) string { xx := x switch xx.(type) { default: return fmt.Sprint("default ", xx) case int, int8, int16, int32: return fmt.Sprint("signed ", xx) case int64: return fmt.Sprint("signed64 ", xx.(int64)) case uint, uint8, uint16, uint32: return fmt.Sprint("unsigned ", xx) case uint64: return fmt.Sprint("unsigned64 ", xx.(uint64)) case nil: return fmt.Sprint("nil ", xx) } panic("not reached") } func check(x interface{}, s string) { w := whatis(x) if w != s { fmt.Println("whatis", x, "=>", w, "!=", s) panic("fail") } w = whatis1(x) if w != s { fmt.Println("whatis1", x, "=>", w, "!=", s) panic("fail") } } func main() { check(1, "signed 1") check(uint(1), "unsigned 1") check(int64(1), "signed64 1") check(uint64(1), "unsigned64 1") check(1.5, "default 1.5") check(nil, "nil ") }