func extractCountryCode()

in phonenumbers.go [2503:2521]

• 18 lines of code
• 6 McCabe index (conditional complexity)

func extractCountryCode(fullNumber, nationalNumber *Builder) int {
	fullNumBytes := fullNumber.Bytes()
	if len(fullNumBytes) == 0 || fullNumBytes[0] == '0' {
		// Country codes do not begin with a '0'.
		return 0
	}
	var (
		potentialCountryCode int
		numberLength         = len(fullNumBytes)
	)
	for i := 1; i <= MAX_LENGTH_COUNTRY_CODE && i <= numberLength; i++ {
		potentialCountryCode, _ = strconv.Atoi(string(fullNumBytes[0:i]))
		if _, ok := countryCodeToRegion[potentialCountryCode]; ok {
			nationalNumber.Write(fullNumBytes[i:])
			return potentialCountryCode
		}
	}
	return 0
}