package main
import (
"fmt"
)
const (
c uint64 = 112
d uint64 = 2147483650111
)
func main() {
var e uint64 = 2147483650111
fmt.Println(byte(c), byte(d), byte(e))
} ask everyone why the constant d returns an error constant 2147483650111 overflows byte when converting to byte . While the variable e is intercepted
go has different conversion rules for constants and nonconstants, see https://golang.org/ref/spec-sharpC..
x-> T, simply translate:
A constant value x can be converted to type T if x is representable by a value of T.
constant conversion must require x to be represented by a value of type T. Here T=byte (0-255) obviously cannot express 2147483650111
A non-constant value x can be converted to type T in any of these cases:
x is assignable to T.
non-constant conversion only needs to be able to assign x to T type. Here, it can be assigned after truncation, which conforms to the conversion rules
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