'0' has the decimal value 48, not zero. '!' has the decimal value 33. Here's a demo program that you can run from your browser: http://play.golang.org/p/qAKG9j5

'0' has the decimal value 48, not zero. '!' has the decimal value 33. Here's a demo program that you can run from your browser: http://play.golang.org/p/qAKG9j5E4V http://play.golang.org/p/qAKG9j5E4V All characters have values greater than or equal to zero.