Problems with prototype

spode

@
#ifndef IMPOSTAZIONI_H
#define IMPOSTAZIONI_H

#include <QSize>

class Impostazioni
{
public:
Impostazioni();
static QSize getScreenSize();
static void setScreenSize(int newScreenWidth, int newScreenHeight);

private:
int screenWidth;
int screenHeight;
};

#endif // IMPOSTAZIONI_H
@

@
#include "impostazioni.h"

Impostazioni::Impostazioni()
{

}

static QSize Impostazioni::getScreenSize()
{
if(screenWidth != 0 || screenHeight != 0)
return QSize(screenWidth, screenHeight);
else
return QSize(320, 640);
}

static void Impostazioni::setScreenSize(int newScreenWidth, int newScreenHeight)
{
screenWidth = newScreenWidth;
screenHeight = newScreenHeight;
}

@

the errors are:
@
..\TemperamentvolleSMS\impostazioni.cpp:8: error: cannot declare member function 'static QSize Impostazioni::getScreenSize()' to have static linkage
..\TemperamentvolleSMS/impostazioni.h: In static member function 'static QSize Impostazioni::getScreenSize()':
..\TemperamentvolleSMS/impostazioni.h:14: error: invalid use of member 'Impostazioni::screenWidth' in static member function
..\TemperamentvolleSMS\impostazioni.cpp:10: error: from this location
..\TemperamentvolleSMS/impostazioni.h:15: error: invalid use of member 'Impostazioni::screenHeight' in static member function
..\TemperamentvolleSMS\impostazioni.cpp:10: error: from this location
..\TemperamentvolleSMS/impostazioni.h:14: error: invalid use of member 'Impostazioni::screenWidth' in static member function
..\TemperamentvolleSMS\impostazioni.cpp:11: error: from this location
..\TemperamentvolleSMS/impostazioni.h:15: error: invalid use of member 'Impostazioni::screenHeight' in static member function
..\TemperamentvolleSMS\impostazioni.cpp:11: error: from this location
..\TemperamentvolleSMS\impostazioni.cpp: At global scope:
..\TemperamentvolleSMS\impostazioni.cpp:16: error: cannot declare member function 'static void Impostazioni::setScreenSize(int, int)' to have static linkage
..\TemperamentvolleSMS/impostazioni.h: In static member function 'static void Impostazioni::setScreenSize(int, int)':
..\TemperamentvolleSMS/impostazioni.h:14: error: invalid use of member 'Impostazioni::screenWidth' in static member function
..\TemperamentvolleSMS\impostazioni.cpp:18: error: from this location
..\TemperamentvolleSMS/impostazioni.h:15: error: invalid use of member 'Impostazioni::screenHeight' in static member function
..\TemperamentvolleSMS\impostazioni.cpp:19: error: from this location
mingw32-make[1]: *** [debug/impostazioni.o] Error 1
mingw32-make: *** [debug] Error 2
The process "C:\QtSDK\mingw\bin\mingw32-make.exe" exited with code 2.
Error while building project TemperamentvolleSMS (target: Qt Simulator)
When executing build step 'Make'
@

sidewinder

And your question is?
Compiler errors are clear: you can't access non static class member variables from a static functions. Create an object of your class inside static function or declare member variables as static as well.

Chuck Gao

Error when define the function.

"static" is not necessary
The variant should be Impostazioni::screenWidth, Impostazioni::screenHeight since they're static
@
QSize Impostazioni::getScreenSize()
{
if(Impostazioni::screenWidth != 0 || Impostazioni::screenHeight != 0)
return QSize(Impostazioni::screenWidth, Impostazioni::screenHeight);
else
return QSize(320, 640);
}

void Impostazioni::setScreenSize(int newScreenWidth, int newScreenHeight)
{
Impostazioni::screenWidth = newScreenWidth;
Impostazioni::screenHeight = newScreenHeight;
}
@

Try again :D

Chuck Gao

Also, make screenWidth and screenHeight as static member

spode

so, i tried:
@
#ifndef IMPOSTAZIONI_H
#define IMPOSTAZIONI_H

#include <QSize>

class Impostazioni
{
public:
Impostazioni();
static QSize getScreenSize();
static void setScreenSize(int newScreenWidth, int newScreenHeight);

private:
static int screenWidth;
static int screenHeight;
};

#endif // IMPOSTAZIONI_H
@

@
#include "impostazioni.h"

Impostazioni::Impostazioni()
{

}

static QSize Impostazioni::getScreenSize()
{
if(Impostazioni::screenWidth != 0 || Impostazioni::screenHeight != 0)
return QSize(Impostazioni::screenWidth, Impostazioni::screenHeight);
else
return QSize(320, 640);
}

static void Impostazioni::setScreenSize(int newScreenWidth, int newScreenHeight)
{
Impostazioni::screenWidth = newScreenWidth;
Impostazioni::screenHeight = newScreenHeight;
}
@

@
..\TemperamentvolleSMS\impostazioni.cpp:8: error: cannot declare member function 'static QSize Impostazioni::getScreenSize()' to have static linkage
..\TemperamentvolleSMS\impostazioni.cpp:16: error: cannot declare member function 'static void Impostazioni::setScreenSize(int, int)' to have static linkage
mingw32-make[1]: Leaving directory `C:/Users/7-Spode/Documents/Progetti/QT/mobile/TemperamentvolleSMS-build-simulator'
mingw32-make[1]: *** [debug/impostazioni.o] Error 1
mingw32-make: *** [debug] Error 2
The process "C:\QtSDK\mingw\bin\mingw32-make.exe" exited with code 2.
Error while building project TemperamentvolleSMS (target: Qt Simulator)
When executing build step 'Make'
@

cincirin

Remove static keyword from implementation code. Leave it only in header definitions

Chuck Gao

As mentioned before, remove "static" in implementation.
You need init your static data member in .cpp file if it's not const

@
// cpp file
int Impostazioni::screenWidth = 0 // like this, in out of function scope

void Impostazioni::setScreenSize(int newScreenWidth, int newScreenHeight)
{
Impostazioni::screenWidth = newScreenWidth; // When using inside class, you can just use screenWidth
Impostazioni::screenHeight = newScreenHeight; // But outside class, you should use Impostazioni::screenHeight if you want to access it(should be public)
}

@