Quote:
If a function has more than one linkage specification, they must agree; it is an error to declare functions as having both C and C++ linkage. Furthermore, if two declarations for a function occur in a program — one with a linkage specification and one without — the declaration with the linkage specification must be first. Any redundant declarations of functions that already have linkage specification are given the linkage specified in the first declaration.
So enough to declare the function as extern "C" once in a header and include this header before any other declaration/definition of the function to make its name C-styled