无法从C++代码调用C共享库方法，求助解决编译报错问题

Hey there! Let's walk through the most common pitfalls when linking a pre-built C shared library to your C++ code via Android.mk, and how to fix them:

Android has strict rules for locating shared libraries, so small mistakes here often break compilation:

• Make sure you’ve defined LOCAL_PREBUILT_SHARED_LIBRARIES in your C++ module’s Android.mk, pointing directly to your compiled .so file. Example:

  LOCAL_PREBUILT_SHARED_LIBRARIES := libc_logger:libs/armeabi-v7a/libc_logger.so
  

• Confirm the library name in LOCAL_SHARED_LIBRARIES matches exactly (omit the .so extension—so use libc_logger instead of libc_logger.so).
• Ensure the ABI of your pre-built .so matches the ABI you’re targeting with your C++ module (e.g., if you’re building for arm64-v8a, your C library must also be compiled for that ABI).

C++ uses name mangling for function signatures, which will break calls to plain C functions unless you explicitly disable it:

• In your C++ code, wrap the C header include in an extern "C" block:

  extern "C" {
  #include "c_logger.h"
  }
  

• For a cleaner fix, add this guard directly to c_logger.h so it works seamlessly with both C and C++:

  #ifdef __cplusplus
  extern "C" {
  #endif
  
  // Your C function declarations here
  void log_message(const char* msg);
  
  #ifdef __cplusplus
  }
  #endif
  

If your C library is part of the same project (not just a standalone .so), ensure modules are properly linked:

• If your C library has its own Android.mk module (e.g., named c_logger), your C++ module’s Android.mk must reference it in LOCAL_SHARED_LIBRARIES and include all sub-makefiles:

  LOCAL_SHARED_LIBRARIES += c_logger
  include $(call all-makefiles-under,$(LOCAL_PATH))
  

• Add the directory containing c_logger.h to your C++ module’s include path with LOCAL_C_INCLUDES:

  LOCAL_C_INCLUDES += $(LOCAL_PATH)/../c_logger_module/include
  

Since you didn’t share the exact error, here are fixes for the most frequent issues:

• Undefined reference to 'log_message': This is 99% a name mangling issue—fix with the extern "C" block above.
• Cannot find library -lc_logger: Your library path/name is incorrect, or the ABI doesn’t match. Double-check LOCAL_PREBUILT_SHARED_LIBRARIES and your NDK ABI settings.
• fatal error: c_logger.h: No such file or directory: Add the correct header path to LOCAL_C_INCLUDES.

Ensure your C shared library was compiled correctly for Android:

• It must be built with -fPIC (Position-Independent Code), required for shared libraries. Check its Android.mk for LOCAL_CFLAGS += -fPIC.
• Use the same NDK version for both the C library and your C++ module—mismatched versions can cause linking errors.

If you’re still hitting issues, sharing the exact error log and snippets of your Android.mk files will help pinpoint the problem faster!

内容的提问来源于stack exchange，提问作者webgenius