error LNK2019: unresolved external symbol - c++

Question

I'm fresh in c++ and I'm facing a problem in including C++ code in Matlab C Mex-file.
I have 5 files: RTIFederate.h, RTIFederate.cpp, RTIFedAmb.cpp, RTIFedAmb.h, RTI3.cpp. RTI3.cpp contains the MEX modules. I'm getting the following errors while compiling with MEX command and libraries:
Creating library C:\Users\Nudel\AppData\Local\Temp\mex_DBx_sv\templib.x and object
C:\Users\Nudel\AppData\Local\Temp\mex_DBx_sv\templib.exp
RTI3.obj : error LNK2019: unresolved external symbol "class rti1516e::ObjectInstanceHandle DistributedParametersLine" (?DistributedParametersLine##3VObjectInstanceHandle#rti1516e##A) referenced in function "void __cdecl mdlOutputs(struct SimStruct_tag *,int)" (?mdlOutputs##YAXPAUSimStruct_tag##H#Z)
RTI3.obj : error LNK2019: unresolved external symbol "class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > * IEC_Model" (?IEC_Model##3PAV?$basic_string#DU?$char_traits#D#std##V?$allocator#D#2##std##A) referenced in function "void __cdecl mdlOutputs(struct SimStruct_tag *,int)" (?mdlOutputs##YAXPAUSimStruct_tag##H#Z)
RTI3.obj : error LNK2019: unresolved external symbol "class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > * IEC_Attribute" (?IEC_Attribute##3PAV?$basic_string#DU?$char_traits#D#std##V?$allocator#D#2##std##A) referenced in function "void __cdecl mdlOutputs(struct SimStruct_tag *,int)" (?mdlOutputs##YAXPAUSimStruct_tag##H#Z)
RTI3.obj : error LNK2019: unresolved external symbol "class rti1516e::ObjectInstanceHandle PowerResource" (?PowerResource##3VObjectInstanceHandle#rti1516e##A) referenced in function "void __cdecl mdlOutputs(struct SimStruct_tag *,int)" (?mdlOutputs##YAXPAUSimStruct_tag##H#Z)
RTI3.obj : error LNK2019: unresolved external symbol "class rti1516e::AttributeHandle * _classattribute" (?_classattribute##3PAVAttributeHandle#rti1516e##A) referenced in function "void __cdecl mdlOutputs(struct SimStruct_tag *,int)" (?mdlOutputs##YAXPAUSimStruct_tag##H#Z)
RTI3.obj : error LNK2019: unresolved external symbol "public: __thiscall RTIFedAmb::RTIFedAmb(void)" (??0RTIFedAmb##QAE#XZ) referenced in function "public: void __thiscall RTIFederate::run(void)" (?run#RTIFederate##QAEXXZ)
RTI3.mexw32 : fatal error LNK1120: 6 unresolved externals
C:\PROGRA~1\MATLAB\R2011B\BIN\MEX.PL: Error: Link of 'RTI3.mexw32' failed
My RTI3.cpp has the following piece of code:
#include "RTIFederate.cpp"
static void mdlOutputs(SimStruct *S, int_T tid)
{
RTIFederate *c = (RTIFederate*) ssGetPWork(S)[0];
// Lê a porta de entrada correspondente
time_T offset = ssGetOffsetTime(S,0);
time_T timeOfNextHit = ssGetT(S) + offset ;
ssSetTNext(S, timeOfNextHit);
for(int_T i=0;i<NUM_INPUTS;i++) {
int *dims = ssGetInputPortDimensions(S, i);
int frameSize = dims[0]; // Tamanho do campo (se for trifasico sera 3 , por ex
int numChannels = dims[1];
if((ssGetInputPortWidth(S,i)<1) ||(ssGetInputPortWidth(S,i)>1)|| (frameSize>1)) {
InputRealPtrsType uPtrs = ssGetInputPortRealSignalPtrs(S, i);
real_T *y = ssGetOutputPortRealSignal(S,i);
int_T width = ssGetOutputPortWidth(S,i);
mexPrintf("%s%d%s%s%d\n","Num da entrada ->",i," ","Num largura > ",width);
for (int_T j=0;j<width;j++){
*y++ =*uPtrs[j];
mexPrintf("%s%u%s\n","IEC_Model[",i,"]--",IEC_Attribute[i].c_str());
if(IEC_Model[i].compare("DistributedParametersLine")!=0) {
if(IEC_Attribute[i].compare("Voltage")) {
mexPrintf("%s%u%s%f\n","Voltage[",j,"]-->",*uPtrs[j]);
c->AtualizaValoresdeAtributos(DistributedParametersLine,_classattribute[0],*uPtrs[j],timeOfNextHit);
} else if(IEC_Attribute[i].compare("Current")) {
mexPrintf("%s%u%s%f\n","Current[",j,"]-->",*uPtrs[j]);
c->AtualizaValoresdeAtributos(DistributedParametersLine,_classattribute[0],*uPtrs[j],timeOfNextHit);
}
} // end if IEC_Model
mexPrintf("%s%f\n","Avanco de tempo1->",timeOfNextHit);
} // end for
} else {
double *u1=(double *) ssGetInputPortSignal(S, i);
real_T *y1 = ssGetOutputPortRealSignal(S,i);
(*y1) =(*u1); //copia entrada para saida
mexPrintf("%s%f\n","Avanco de tempo2->",timeOfNextHit);
c->AtualizaValoresdeAtributos(PowerResource,_classattribute[0],*u1,timeOfNextHit);
} // end else
} // end for i
}
/* Function: mdlTerminate */
static void mdlStart(SimStruct *S)
{
char *buf;
size_t buflen;
int status;
buflen = mxGetN((ssGetSFcnParam(S, 2)))*sizeof(mxChar)+1 ; // read 3rd param
buf = (char *)mxMalloc(buflen); //alloc mem
status = mxGetString((ssGetSFcnParam(S, 2)), buf,(mwSize)buflen);
ssGetPWork(S)[0] = (void *) new RTIFederate; // store new C++ object in the
RTIFederate *c = (RTIFederate *) ssGetPWork(S)[0];
c->InterpretaArqMDL(buf); // Rotina que trata da interpretacao dos objetos da norma IEC 61968
c->run();
...
}
On top of RTIFederate.cpp I have declared the following:
#include "RTIFedAmb.h"
#include "RTIFederate.h"
and in the file RTIFederate.h I declared:
class RTIFederate
{
public:
RTIambassador *rtiamb;
RTIFedAmb *fedamb;
// variables //
ObjectClassHandle _ClassObject[300];
AttributeHandle _classattribute[300];
string IEC_Model[29],IEC_Attribute[20];//
// public methods //
RTIFederate();
virtual ~RTIFederate();
...
}
extern ObjectClassHandle _ClassObject[300];
extern AttributeHandle _classattribute[300];
extern AttributeHandleSet attributeSet[300];
extern ObjectInstanceHandle ProtectedSwitch,Recloser,ThreePhaseBreaker,ACLineSegment,DistributedParametersLine;
extern RTIambassador *rtiamb;
extern RTIFedAmb *fedamb;
Also there is a piece of code in RTIFedAmb.h:
//methods
RTIFedAmb();
virtual ~RTIFedAmb() throw();
Can anyone help me to explain what am I missing ?

Answer 1

So, you want to include c-lib in your c ++ project. That's fine but you should note one thing: c ++ differs a bit from c. And you found a good illustration.
c ++ "deforms" function names in lib while c does not. Nevertheless you still can use c libraries. Do it so:
extern "C" ObjectClassHandle _ClassObject[300];
extern "C" AttributeHandle _classattribute[300];
extern "C" AttributeHandleSet attributeSet[300];
extern "C" ObjectInstanceHandle ProtectedSwitch,Recloser,ThreePhaseBreaker,ACLineSegment,DistributedParametersLine;
extern "C" RTIambassador *rtiamb;
extern "C" RTIFedAmb *fedamb;
Hope it will help you.