func isIPV4(IP string) bool {
    arr := strings.Split(IP, ".")
    if len(arr) != 4 {
        return false
    }
    for _, elem := range arr {
        if elem == "" {
            return false
        }
        if len(elem) > 1 && elem[0] == '0' {
            return false
        }
        num := 0
        for _, c := range elem {
            if c >= '0' && c <= '9' {
                num = num*10 + int(c - '0')
            }else{
                return false
            }
        }
        if num > 255 {
            return false
        }
    }
    return true
}

//IPV6地址的判断：
//1. 用“：”分割字符串，若长度不等于8，则return Neither
//2. 遍历每一个数组的每一个元素，若元素的长度大于4，则return Neither
//3. 判断每一个元素的字符，若出现非0-9，A-F的字符，则return Neither
func isIPV6(IP string) bool {
    IP = strings.ToUpper(IP)
    arr := strings.Split(IP, ":")
    if len(arr) != 8 {
        return false
    }
    for _, elem := range arr {
        if elem == "" || len(elem) > 4{
            return false
        }
        
        for _, c := range elem {
            if (c >= '0' && c <= '9') || (c >= 'A' && c <= 'F'){
                continue
            }else{
                return false
            }
        }
    }
    return true
}