Yes, Oracle gives options to do cross platform Dataguard.
Please refer to "Data Guard Support for Heterogeneous Primary and Physical Standbys in Same Data Guard Configuration (Doc ID 413484.1)" for more details.
There are some restrictions and limitations which you can consider for your exact environment before attempting.
You cannot create oracle data guard across different operating system. The primary and standby should be of same operating system.
No offense, but your statement is not true. While there are limits you can in fact use different operating systems.
As stated by nagulan.selvakumar, this is the correct document to confirm this:
Data Guard Support for Heterogeneous Primary and Physical Standbys in Same Data Guard Configuration (Doc ID 413484.1)
I have gone through the document, it had mentioned that you can configure dataguard on same OS family.
so I would like to know can i have my primary database on linux OS and my standby database on Windows OS.
Yes you can.
Review the chart in the same document for requirements and patches.
As mentioned by selvakumar, you can go through the MOS Note ( 413484.1).
If that doesn't help. Alternatively, you can implement Oracle Golden Gate for Data replication from Primary to Standby.