I have windows 10 and Ubuntu 17.01 dually booted!. I want to install the Ubuntu 18.04 How I can do so without affecting my windows and the data stored on my hard-disk.
First, there isn't a 17.01 version of Ubuntu. I've never experienced any problems upgrading from six previous versions to a current version. I tested upgrading from 14.04 to 18.04 to test and answer recently provided in an 18.04 upgrade question. So an upgrade is possible. If you have data on your 17.XX version, you wouldn't lose that data when using the upgrade option. As far as your Windows partition, it wouldn't be touched using any of the options unless you specify to format that partition.
When you install Ubuntu you have the option of choosing the type of install. You can specify where you want it to be installed. Of course, if you choose the erase and use the whole disk, everything on the disk would be gone. The install alongside Windows option will resize the Windows partition and use the specified space for Ubuntu. The Windows wouldn't data would be fully preserved.
The do something else option will allow you to specify where you want the install to occur. In this type, the data Ubuntu system files directories will be replaced with the new Ubuntu system files, while your Ubuntu data will remain unless you specify the format partition option.
Yes. You can surely install Ubuntu 18.04 in the hard disk along with Windows 10 without affecting files. First of all boot, the Ubuntu 18.04 iso which is suitable for your system from a USB drive and choose a different partition in the disk other than the Windows 10 system partition.
Other option is updating the 17.04 or 17.10 to 18.0 directly. You can update the Ubuntu 17.04 or 17.10 from Ubuntu Softwares and Updates.