Ip地址转32位整数

int ipToInt(string s)
{
    int ret = 0;
    int num = 0;

    for (int i = 0; i < s.size(); i++)
    {
        if (s[i] != ‘.‘)
        {
            num = num * 10 + (s[i]-‘0‘);
        }
        else
        {
            ret <<= 8;
            ret += num;
            num = 0;
        }
    }
    ret <<= 8;
    ret += num;

    return ret;
}