Undefined symbol on node.js addon

Question

I'm trying to create some node.js addons. Inside the addon i have a call to a static lib. Everything compiles ok, but when i call my addon function from javascript, i get the following:

module.js:356
  Module._extensions[extension](this, filename);
                           ^
Error: /home/.../Projects/NodeAddonComLibTest/build/Debug/addon.node: undefined symbol: _Z6ctest1Pi
    at Module.load (module.js:356:32)
    at Function.Module._load (module.js:312:12)
    at Module.require (module.js:364:17)
    at require (module.js:380:17)
    at Object.<anonymous> (/home/.../Projects/NodeAddonComLibTest/doTest.js:1:75)
    at Module._compile (module.js:456:26)
    at Object.Module._extensions..js (module.js:474:10)
    at Module.load (module.js:356:32)
    at Function.Module._load (module.js:312:12)
    at Function.Module.runMain (module.js:497:10)

My addon code is the following:

#include <iostream>
#include <string.h>
#include <stdlib.h>

#include <node.h>
#include <v8.h>

using namespace v8;
using namespace std;

void ctest1(int *);

Handle<Value> setPort(const Arguments& args){
HandleScope scope;

if (args.Length() != 1) {
    ThrowException(Exception::TypeError(String::New("Wrong number of arguments.")));
    return scope.Close(Undefined());
}

// =========================
printf("Calling static lib...\n");
int x=0;
ctest1(&x);
printf("Val c=%d\n", x);
// =========================

return scope.Close(Number::New(args[0]->NumberValue()));
}

void Init(Handle<Object> exports) {
exports->Set(String::NewSymbol("show"), FunctionTemplate::New(setPort)->GetFunction());
}

NODE_MODULE(addon, Init)

Can someone help?

Thanks

Answer 1

The void ctest1(int *); must be declared it with extern "C":

extern "C" {
    void ctest1(int *);
}