Need help with "primary-expression" error

kspill2 · #1 10-Sep-2007, 20:34

Hi everyone. I pretty new to C/C++. Heres my code:

CPP / C++ / C Code:

#include "Environment.h"

int Environment :: nExist = 0;
int Environment :: nCreated = 0;

Environment :: Environment(void){
        serNo = ++nCreated;
        nExist++;

        char buffer[100];
        sprintf(buffer, "Environment%d", serNo);
        label = new char[strlen(buffer) + 1];
        strcpy(label, buffer);
        return;
}//Environment :: Environment(void)

CPP / C++ / C Code:

#ifndef SIMULATION_H
#define SIMULATION_H

#include "Environment.cpp"

using namespace std;

class Simulation {
        private:
        Environment env;
        int serNo;
        static int nExist, nCreated;

        public:
        Simulation(void);
        Simulation(const Environment *);
Simulation(const Simulation&);
        ~Simulation();

        const Simulation & operator = (const Simulation&);

        void print(void) const;
};

CPP / C++ / C Code:

#include "Simulation.h"

int Simulation :: nExist = 0;
int Simulation :: nCreated = 0;

Simulation :: Simulation(void){
        serNo = ++nCreated;
        nExist++;
        env = new Environment(void);

        return;
}//Simulation :: Simulation(void)

Heres the Error:

CPP / C++ / C Code:

Simulation.cpp: In constructor `Simulation::Simulation()':
Simulation.cpp:9: error: expected primary-expression before "void"

Any help would be greatly appreciated

Kimmo · #2 11-Sep-2007, 00:25

Try

CPP / C++ / C Code:

env = new Environment();

instead of

CPP / C++ / C Code:

env = new Environment(void);

(Assuming that is the line in question.)

I don't know if it helps, but looks like it could.

Other than that... There are just so many things "weird" or "wrong" or "missing" in your code, I wouldn't know where to begin listing.

Peter_APIIT · #3 11-Sep-2007, 06:13

Simulation(const Environment *);

Use reference instead of pointer or pass by value.

I hope this help.

Kimmo · #4 14-Sep-2007, 10:54

I'll try to point out some things to consider in the future, when posting question and in general.

CPP / C++ / C Code:

#include "Environment.h"

We have no way of knowing what exactly is contained in "Environment.h", so including this kind of #include directives in code you post here on the forums without actually including the code from "Environment.h" is useless. This also renders the the following code useless because, apparently, the following code depends on the class inside "Environment.h" to which we have no access.

So considering your post here, this piece of code is just useless overhead for us.

CPP / C++ / C Code:

Environment :: Environment(void)

The C++ way of telling "no arguments" is just (), not (void).

CPP / C++ / C Code:

        char buffer[100];
        sprintf(buffer, "Environment%d", serNo);
        label = new char[strlen(buffer) + 1];
        strcpy(label, buffer);
        return;

My C knowledge is nonexistant, but does this mean you put "Environment" + serNo to buffer, then allocate memory for label, and then copy buffer to label?

If label is just a "string", you might want to take a look at the C++ string class. Also, did you take into account the use of dynamic memory allocation in your destructor, copy constructor and assignment operator? That's another reason why using std::string would be handier.

You don't actually need the return statement at the end.

CPP / C++ / C Code:

#ifndef SIMULATION_H
#define SIMULATION_H

You miss the terminating #endif.

CPP / C++ / C Code:

#include "Environment.cpp"

I can't really say anything about this. Usually, I think, we #include only headers and compile and link source files. I don't know how this would affect your whole program. Your Environment.cpp doesn't seem to be safeguarded with #ifndef (and why should it.. We usually just link them) though, so including this should at least create some compile errors right?

In any way, your class Simulation doesn't need to know about the implementation of class Environment. It just needs the declaration.

CPP / C++ / C Code:

using namespace std;

Umm... What is this for? I mean, I don't see any names from namespace std in your class declaration, so why would you need this? It's also generally a bad habit to include the whole namespace, but I guess you haven't been to namespaces yet, so it's quite okay. (Except for the fact you don't use the names.)

CPP / C++ / C Code:

class Simulation {
        private:
        Environment env;

You need a decent Environment assignment operator and/or copy constructor to properly copy this member object.

CPP / C++ / C Code:

        ~Simulation();

This wouldn't compile anyway without the definition of destructor. If you provide the declaration, you have to provide the definition.

CPP / C++ / C Code:

        const Simulation & operator = (const Simulation&);

The return value should probably be without the const qualifier..?

cpp]
#include "Simulation.h"

CPP / C++ / C Code:

        env = new Environment(void);

Dynamic memory allocation and non-defined destructor = bad things. Besides, the way I see it, your env is just an Environment data member, not a pointer to an Environment. So this shouldn't actually compile right?

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Need help with "primary-expression" error

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