using-ctype

Python binding using ctype

Assuming there is already a shared c library, we can load this in python using following statement.

 
shared_lib = "path to shared library"
c_lib = ctype.CDDL(shared_lib)

c_lib has all the function present in shared library as attributes.

Let’s see there is a function mul which takes an integer and a float and returns the product of it as float.

By default, ctype marshalling process passes all the data as integer so we need to explicitly tell ctype to use float.

c_lib.mul(2, ctype.c_float(2.3)) ## FAILS

The above statement fails. The reason being the return type is float and marshalling is not happening correctly from ctype end. Again we need to specify it.

c_lib.mul.restype = ctype.c_float

Now, it will work.