CODEWITHSUNDEEP
c++structheader
King Broos
King Broos

Reputation: 11

Unable to use struct defined in different header file

I have a project where I need to expand some functionality without touching the project I'm using.

The core of the problem is this (I dumbed it down but the core should be clear).

//Layout.h
#ifndef LAYOUT_H
#define LAYOUT_H

#include "Speaker.h"

class Layout
{
    public:
        //unrelated stuff
    private:
        LSS::Speaker temp;
};
#endif

//Speaker.h"
#ifndef SPEAKER_H
#define SPEAKER_H
namespace LSS
{
    struct Speaker
    {
        Speaker(int val1, float val2)
        :some_int(val1)
        , some_float(val2)
        {
        }

        ~Speaker()    
        {
            //do other stuff
        }

         int some_int;
         float some_float;

    };//struct Speaker
}
#endif

I just want to be able to use the struct Speaker (as defined in "Speaker.h") in "Layout.h" without touching "Speaker.h"

If I compile I get following errors:

Error 22 error C2512: 'LSS::Speaker' : no appropriate default constructor > available Layout.cpp 7 1 MyProj

I think that wraps it up - any help would be appreciated, I'm pretty new to c++

Edit: in recreating the issue I made a TYPO (LSS: instead of LSS::). Updated the compiler error

Upvotes: 0

Views: 106

Answers (3)

Mike Seymour
Mike Seymour

Reputation: 254431

To answer the new question, now it's been changed to invalidate previous answers:

'LSS::Speaker' : no appropriate default constructor

As the error message says, the class has no default constructor, so it can only be instantiated by providing constructor arguments. You probably want to do this in the Layout constructor(s), for example:

Layout() : temp(some_value, some_other_value) {}

Upvotes: 0

VolAnd
VolAnd

Reputation: 6407

Read carefully message

Error 3 error C2146: syntax error : missing ';' before identifier 'temp' > Layout.h 102 1

and then change LSS:Speaker temp; to LSS::Speaker temp;

EDIT:

For error

Error 22 error C2512: 'LSS::Speaker' : no appropriate default constructor > available Layout.cpp 7 1 MyProj

if you provide at least one constructor with parameters for Speaker, you also have to provide default constructor (constructor without parameters) to make LSS::Speaker temp; valid. It is a rule (for cases when no constructors are written by programmer compiler make default constructor, but if programmer start changing construction logic, compiler do nothing in this part of work).

Or you can provide default values in the existing constructor, like this:

  Speaker(int val1 = 0, float val2 = 0.0f)
        :some_int(val1)
        ,some_float(val2)
  {
  }

Upvotes: 1

King Broos
King Broos

Reputation: 11

I figured out how to work around Layouts.h not having a default constructor (remember: in this case I wasn't allowed to edit the Speaker() struct)

In Layout.h I defined 

class Speaker: public LSS::Speaker
{
    public:
        Speaker(): LSS::Speaker(-1, 0.0f){}
};

'Overloading' the missing constructor (that I couldn't fill in myself.

Problem solved :)

Upvotes: 0

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