Question

I’ve removed “use precompiled header” option from crypto.c.

How to resolve this error properly?

Answer 1

You need to declare tha crypt() function as extern "C" in its header file, like this:

#ifdef __cplusplus
extern "C" {
#endif

void crypt(unsigned int *, unsigned int, unsigned int *);

#ifdef __cplusplus
}
#endif

If you don’t, C++ compilers will treat it as a function with C++ (as opposed to C) linkage and will apply name mangling on it.