1108. IP 地址无效化

char * defangIPaddr(char * address){
    if (address == NULL)
        return NULL;
    int addressLength = strlen(address);
    char *res = malloc(addressLength + 7);
    char *tmp = res;
    while (*address != '') {
        if (*address == '.') {
            *tmp = '[';
            tmp++;
            *tmp = '.';
            tmp++;
            *tmp = ']';
        }
        else
            *tmp = *address;
        tmp++;
        address++;
    }
    *tmp = '';
    return res;
}