On Sat Apr 9, 2022 at 3:56 PM CEST, 'Jack Li' via golang-nuts wrote: > Why literal operation is exact, variable is not? > > fmt.Println(0.1 + 0.2) // 0.3 exactly > fmt.Println(x + y) // 0.30000000000000004 >
Both aren't exact because floats can't represent 0.3 exactly, they differ because literals and constants expressions have arbitrary precision (http://golang.org/ref/spec/#Constants), so "0.1" and "0.2" in "0.1 + 0.2" are exact, then when the exact "0.3" result is converted to a float64 it becomes the closest possible, You can check this if you ask to print with more precision x, y := 0.1, 0.2 fmt.Printf("%.17f...\n", 0.1+0.2) // 0.29999999999999999... fmt.Printf("%.17f...\n", x+y) // 0.30000000000000004... https://go.dev/play/p/2qSfoCZGaD6 -w -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. To unsubscribe from this group and stop receiving emails from it, send an email to golang-nuts+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/golang-nuts/CJ6VDO2DK4XB.3VDUG02EUZ58S%40pampas.
