class header warnings.

[impeteperry]

I am confused obout declaring a class header.
If I daclare a class

class Products: public QWidget
{
Q_OBJECT
public:
Products( QWidget *parent = 0, const char *name = 0);

and the constructor

Products::Products( QWidget *parent, const char *name )
{
}

I get the warnings

products.cpp:40: warning: unused parameter ‘parent’
products.cpp:40: warning: unused parameter ‘name’
products.cpp:40: warning: unused parameter ‘parent’
products.cpp:40: warning: unused parameter ‘name’

I would appreciate some help. thanks

[munna]

It should be

Products::Products( QWidget *parent, const char *name ) : QWidget(parent,name)
{
 
}

Products::Products( QWidget *parent, const char *name ) : QWidget(parent,name)
{

}

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[impeteperry]

when I have

Products::Products( QWidget *parent, const char *name ) : QWidget(parent,name)
{
}

Products::Products( QWidget *parent, const char *name ) : QWidget(parent,name)
{
}

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as you suggest, I get

products.cpp:42: error: no matching function for call to ‘QWidget::QWidget(QWidget*&, const char*&)’
/usr/local/Trolltech/Qt-4.1.1/include/QtGui/qwidget.h:635: note: candidates are: QWidget::QWidget(const QWidget&)
/usr/local/Trolltech/Qt-4.1.1/include/QtGui/qwidget.h:596: note: QWidget::QWidget(QWidgetPrivate&, QWidget*, Qt::WFlags)
/usr/local/Trolltech/Qt-4.1.1/include/QtGui/qwidget.h:183: note: QWidget::QWidget(QWidget*, Qt::WFlags)

In Qt3 I had what you suggested. I am using 4.1 in Ubuntu/Kubuntu 5.10.

[jpn]

QWidget's ctor does not take a "const char*" parameter in Qt 4:
QWidget::QWidget ( QWidget * parent = 0, Qt::WFlags f = 0 )

[munna]

oh, then you can either use

Products::Products( QWidget *parent, const char *name ) : QWidget(parent)
{
  setObjectName(name);
}

Products::Products( QWidget *parent, const char *name ) : QWidget(parent)
{
  setObjectName(name);
}

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or, if you dont use the parameter "name"

class Products: public QWidget
{
Q_OBJECT
public:
Products( QWidget *parent = 0);

class Products: public QWidget
{
Q_OBJECT
public:
Products( QWidget *parent = 0);

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and the constructor

Products::Products( QWidget *parent ) : QWidget(parent)
{
 
}

Products::Products( QWidget *parent ) : QWidget(parent)
{

}

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[guestgulkan]

While it is true that in this case you should really pass on the parent pointer and name pointer to the parent QWidget, that is not the reason for the warning message.

If you declare variables but do not do use them, then the compiler will issue this warning.

[impeteperry]

Thanks munna. Now I have to go back to the books for why
and guestgulkan, I am aware of that, but what I don't understand is why it worked in Qt3 and not in Qt4. I have never really understood what this whole class declaration is in Qt anyway.

Thanks to you both.

[munna]

but what I don't understand is why it worked in Qt3 and not in Qt4

because the constructor declaration in Qt3 is different from that of Qt4. You can find more about all this in the Qt Assistant.

have never really understood what this whole class declaration is in Qt anyway

It is the way you do it in C++. I think you need to first learn more about C++.

[impeteperry]

I have not run across this in my c++ programming. This sample is taken from my program that designs multi-story precast concrete structures.

class Sidesway
	{
	protected:
		float accumulated_area[20];
		float column_length[20];
		float length_factor[20];
		float left_el_length[20];

class Sidesway
	{
	protected:
		float accumulated_area[20];
		float column_length[20];
		float length_factor[20];
		float left_el_length[20];

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and the constructor

#include "extern.h"
#include "sidesway.h"
#include "matrix.h"
extern Sidesway SW, SW_O, SW_U;
extern Matrix A, E, F, G, K, L, M, N, P, Q, R, S, V, W, Z;
 
Sidesway::Sidesway ()
	{
	unsigned n = 25 * 4 * 20;
	n += 11 * 3 * 4 * 20;
	n += 3 * 4 * 4 * 20;
	n += 2 * 3 * 4;
 	n += 7 * 2 * 20;

#include "extern.h"
#include "sidesway.h"
#include "matrix.h"
extern Sidesway SW, SW_O, SW_U;
extern Matrix A, E, F, G, K, L, M, N, P, Q, R, S, V, W, Z;

Sidesway::Sidesway ()
	{
	unsigned n = 25 * 4 * 20;
	n += 11 * 3 * 4 * 20;
	n += 3 * 4 * 4 * 20;
	n += 2 * 3 * 4;
 	n += 7 * 2 * 20;

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Have I been missing somthing for the last 25 years?

[munna]

What you do is fine. But there are better ways of doing.

You can make your program more flexible and cleaner by using the other c++ techniques.

It is all very simple. Any c++ tutorial website or c++ book will have everything that you need to undertand things in Qt.