relic does not work with C++

[yuchen1024]

I am trying to write a C++ program using relic. However, I always run into the following issues when compiling and linking.
The environment is MAC OS.

The MWE is as below:

#include "relic.h"
#include <iostream>
using namespace std; 

int main()
{
	bn_t master; 
	bn_t n;
	int result = RLC_OK;

	bn_null(n);
	bn_null(master); 

	TRY {
		bn_new(n);
		bn_new(master); 

		g1_get_ord(n);
		bn_rand_mod(master, n);
	}
	CATCH_ANY {
		result = RLC_ERR;
	}
	FINALLY {
		bn_free(n);
		bn_free(master)
	}

	cout << "hello, 2021" << endl; 
	return 0; 
}   

compile and link

g++  -std=c++11 -o test_MWE  MWE.cpp -L /usr/local/lib -l librelic_s.a -I /usr/local/include/relic

error information is as below:

Undefined symbols for architecture x86_64:
"bn_rand_mod(bn_st*, bn_st*)", referenced from:
_main in MVE-a0d2da.o
"ep_curve_get_ord(bn_st*)", referenced from:
_main in MVE-a0d2da.o
"bn_init(bn_st*, int)", referenced from:
_main in MVE-a0d2da.o
"core_get()", referenced from:
_main in MVE-a0d2da.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)

Could anyone help me to solve this issue?

[yuchen1024]

"Since C++ has overloading of function names and C does not, the C++ compiler cannot just use the function name as a unique id to link to, so it mangles the name by adding information about the arguments."
quote from https://stackoverflow.com/questions/1041866/what-is-the-effect-of-extern-c-in-c

extern "C" {
#include "relic.h"
}
fixes this issue