structures and classes

[OzQTNoob]

I was wanting to know if it is considered bad practice to declare a structure in my class? a snippet of the class definition below,

#ifndef READHEADER_H
#define READHEADER_H
 
#include <QObject>
...
 
struct headerInfo{
    int numberOfSamples;
    int numberOfLines;
    int numberOfBands;
    int dataType;
    QString fileName;
    QVector<double> wavelengths;
};
 
class readHeader : public QObject
{
    Q_OBJECT
public:
    explicit readHeader(QObject *parent = 0);
    headerInfo getHeaderInfo();
...
private:
...
signals:
...    
public slots:
 
private:
...
    headerInfo p_hdrinfo;
};
 
#endif // READHEADER_H

#ifndef READHEADER_H
#define READHEADER_H

#include <QObject>
...

struct headerInfo{
    int numberOfSamples;
    int numberOfLines;
    int numberOfBands;
    int dataType;
    QString fileName;
    QVector<double> wavelengths;
};

class readHeader : public QObject
{
    Q_OBJECT
public:
    explicit readHeader(QObject *parent = 0);
    headerInfo getHeaderInfo();
...
private:
...
signals:
...    
public slots:

private:
...
    headerInfo p_hdrinfo;
};

#endif // READHEADER_H

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So in my main program when include my readheader.h I can of course access the structure directly, but instead I use the getheaderinfo function which returns the structure(i don't really know what my reasoning behind that was). This code/class will never be distributed to anyone and any code that does use it will be writing. I am aware that the way I have done it also allows the structure contents to be changed anywhere in my code. Doesn't feel right.
I should also say that the header file contains various information in various formats e.g. int, double, string and some vectors.
I cant help but feel that this is not the right thing to do and is most likely considered really bad practice. I am still very new to C++ and Qt. I did initially have a ton of getter public functions in my class but wanted to return everything at once rather than making umpteen million calls.

Any help/advice on such things would be really appreciated.

Cheers
Oz

[wysota]

If the structure is tightly related to the class, it can be declared as in your code however it might be better to declare it inside the class.

class readHeader : ... {
public:
  struct headerInfo {
    int numberOfSamples;
    int numberOfLines;
    // ...
  };
 
  headerInfo getHeaderInfo() const { ... }
};

class readHeader : ... {
public:
  struct headerInfo {
    int numberOfSamples;
    int numberOfLines;
    // ...
  };

  headerInfo getHeaderInfo() const { ... }
};

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Note that the fully qualified name of the struct then becomes readHeader::headerInfo.

[AlexSudnik]

I don't think i'm the one who can give an advice about "best practices"...
Anyway , what do you mean "I can of course access the structure directly" ? Maybe i'm missing something but it seems like you're confusing type's declaration with a type's instance. You've got a structure's declaration placed in a header file : that's it , this way you can do this :

// in wherver header/source file the readheader.h is included //
 
headerInfo newHeaderInfoObject ; 
 
newHeaderInfoObject.numberOfSamples = 10 ; 
// ...
// etc.

// in wherver header/source file the readheader.h is included //

headerInfo newHeaderInfoObject ; 

newHeaderInfoObject.numberOfSamples = 10 ; 
// ...
// etc.

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However , If you had the headerInfo declaration placed within a readHeader class :

// in wherver header/source file the readheader.h is included //
 
readHeader::headerInfo newHeaderInfoObject ; // if headerInfo declaration is placed in a PRIVATE section : ERROR 
 
readHeader::headerInfo newHeaderInfoObject ; // if headerInfo declaration is placed in a PROTECTED section : ERROR 
 
readHeader::headerInfo newHeaderInfoObject ; // if headerInfo declaration is placed in a PUBLIC section : OK

// in wherver header/source file the readheader.h is included //

readHeader::headerInfo newHeaderInfoObject ; // if headerInfo declaration is placed in a PRIVATE section : ERROR 

readHeader::headerInfo newHeaderInfoObject ; // if headerInfo declaration is placed in a PROTECTED section : ERROR 

readHeader::headerInfo newHeaderInfoObject ; // if headerInfo declaration is placed in a PUBLIC section : OK

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But , getting back to "I can of course access the structure directly" : since you've placed "headerInfo p_hdrinfo" in the PRIVATE section , there is no way you can access it directly .Isn't it the reason you've created methods for accessing it ?^^ So , depending on how you're gonna use the readHeader class in your application's data architecture , you'll probably have to place it in either PRIVATE or PROTECTED sections...