Using c library in c++ code with makefile - c++

Question

I have a C library made by cluster.h and cluster.c. I compiled that with gcc -c cluster.c.
I have to use a method of this library in the main class of a C++ project. This is the makefile i use:
abundancebin: main.o profileManager.o myHash.o myMalloc.o myStack.o myStringHash.o
g++ -o abundancebin main.o profileManager.o myHash.o myMalloc.o myStack.o myStringHash.o
main.o: main.cpp
g++ -c main.cpp
profileManager.o: profileManager.cpp
g++ -c profileManager.cpp
myHash.o: myHash.cpp
g++ -c myHash.cpp
myMalloc.o: myMalloc.cpp
g++ -c myMalloc.cpp
myStack.o: myStack.cpp
g++ -c myStack.cpp
myStringHash.o: myStringHash.cpp
g++ -c myStringHash.cpp
clean:
-rm *.o abundancebin
I tried to import the C library in main.cpp using after other imports:
#ifdef __cplusplus
extern "C" {
#endif
#include <cluster.h>
#ifdef __cplusplus
}
#endif
but when i compile with make i have this response:
main.cpp:29:21: fatal error: cluster.h: No such file or directory
#include <cluster.h>
^
compilation terminated.
make: *** [main.o] Error 1
if i use "cluster.h" instead of i have this error:
main.o:main.cpp:(.text+0xf68): riferimento non definito a "kmedoids"
main.o:main.cpp:(.text+0xf68): rilocazione adattata per troncamento: R_X86_64_PC32 contro il simbolo non definito "kmedoids"
/usr/bin/ld: main.o: bad reloc address 0x18 in section.xdata'
collect2: error: ld returned 1 exit status
make: * [abundancebin] Error 1`
I also tried to copy the code part i need from C library to C++ project but the compiler reports many errors like this:
error: invalid conversion from ‘void*’ to ‘int*’ [-fpermissive]
vector = malloc(nnodes*sizeof(int));
The library files are in the same folder of the project files. Can someone help?
Thank you

Answer 1

If you want to add some code which is wrote in c language, you have to #include it like:
extern "C" {
#include "x264.h"
}
which tell compiler to deal with it differently, and its not necessary to change your code to c++
1: you add your code as: #include <cluster.h>
its better to change it to: #include "cluster.h"
the different is, the second one tell the compiler to first search for your header in the current directory and then in the main c++ libraries directory
your error:
main.cpp:29:21: fatal error: cluster.h: No such file or directory
is because it can't find the header, so, if cluster.h is in the same directory as main.cpp, use #include "cluster.h"
or you can use -I. (which tell its in the current directory) or -I/address to tell compiler where to look for your header
when you correct it, you get the second error, which I believe its because of your code, and I think its because of your code in main.cpp, and do not have anything with your cluster code, I suggest, try to post your code to find out what's the problem

Answer 2

In answer to your question, I would approach it something like this in the makefile:
all: cfile.o
g++ main.cpp -o app
cfile.o: cluster.c cluster.h
gcc -c cluster.c
Note: This assumes that everything is in the same directory, so take care to specify paths if not.
Let me know of any further errors.