Golang: somewhat faster string uppercase / lowercase (for certain strings)

upperlower.go

// See: https://groups.google.com/forum/#!topic/golang-nuts/Il2DX4xpW3w

// A slightly faster lowercase function.
func toLower(s string) string {
	b := make([]byte, len(s))
	for i := range b {
		c := s[i]
		if c >= 'A' && c <= 'Z' {
			c += 'a' - 'A'
		}
		b[i] = c
	}
	return string(b)
}

// A slightly faster uppercase function.
func toUpper(s string) string {
	b := make([]byte, len(s))
	for i := range b {
		c := s[i]
		if c >= 'a' && c <= 'z' {
			c -= 'a' - 'A'
		}
		b[i] = c
	}
	return string(b)
}

Unfortunately, it can be used only with latin symbols...

Depends on what ya need 🤷