Linking error. Problem on "undefined reference to...." in NIOS II IDE 11sp1

[Altera_Forum]

hello! 

I am new in quartus 11 and NIOS II IDE 11sp1 for development. The project concludes four source files. the main() function is in    my_file_for_blank_project_0.cpp   the other three source files all have their corsponding H files included in my_file_for_blank_project_0.cpp.   But when I build project, the console shows :       **** Build of configuration Debug for project my_blank_project_0 ****   make -s all includes  Compiling file_sys.c... Compiling hal.c... Compiling host.c... Compiling my_file_for_blank_project_0.cpp... Linking my_blank_project_0.elf... obj/my_file_for_blank_project_0.o(.text+0x1c4): In function `main': ../my_file_for_blank_project_0.cpp:46: undefined reference to `host()' collect2: ld returned 1 exit status make: *** [my_blank_project_0.elf] Error 1   the host() function is in host.c and also declared in host.h. the corresponding four *.o files can also be produced.   I do not know how to solve it. Can anyone with kindness help me?

[Altera_Forum]

I think this happens because your are mixing C and C++ source files. 

For example, If you want to call C++ code from a C source file you need the following definition in .cpp file:  extern "C" int test_cpp_call (int n);  int test_cpp_call (int n) {  .... }