Question: Can we include static variable in header files.
If yes,Can other files can access it ?

Can we include static function in header files and use it in another files.

Can we pass static variable as function arguments ?suppose some function is there in header file header.h :

fun(static int a,static int b)

Answer: 
This is incorrect coding practice to use static variable in header files.
Also static limits the scope of variable to a file. So, static variable of file1.c can't be accessed from file2.c
1. A static variable **can be defined in the header file.** But doing so, the result will be having a **private copy of that variable in each source file which includes the header file**. So it will be wise not to declare a static variable in header file, unless you are dealing with a different scenario.
2. **Same applies for static function.**
3. Trying to apply static to a function argument doesn't make much sense, so the **standard doesn't allow it** (§6.7.5.3/2: "The only storage-class specifier that shall occur in a parameter declaration is register.")
**trying to enter static variable as an argument type results in error.**