How to define static members in a static function in .cpp file?

[thippu]

@jsulm okay.

ampconfiguration.h

static double sampling_rate;
int getSampling_rate()const;
void setSampling_rate(int value);

static void ReadIni();

ampconfiguration.cpp

void AmpConfiguration::ReadIni()
{
   QFile fp("AmpConfiguration.txt");
   if(!fp.open(QIODevice::ReadOnly)
  {
     QMessageBox::information::(nullptr,"file error","file not found",QMessageBox::Ok);
  }
QStringList *line_list=new QStringList;
QTextStream txt_stream(&fp);
while(!txt_stream.atEnd())
{
  QString line=txt_stream.readLine();
  QStringList temp=line.split("=",QString::SkipEmptyParts);
  line_list->push_back(temp.at(1));
 }
   sampling_rate=line_list->at(0).toDouble();
}
//I am getting error in the building itself not on the runtime.

[jsulm]

@thippu Not really what I asked...
Did you add

double AmpConfiguration::sampling_rate;

to your cpp file?

[thippu]

@jsulm said in How to define static members in a static function in .cpp file?:

double AmpConfiguration::sampling_rate;

double AmpConfiguration::sampling_rate=10.2 //like this? in the static function?

[jsulm]

@thippu said in How to define static members in a static function in .cpp file?:

in the static function?

No. Like this:

double AmpConfiguration::sampling_rate=10.2;
void AmpConfiguration::ReadIni()

See https://en.cppreference.com/w/cpp/language/static

[thippu]

@jsulm yes bro, I did add like this double AmpConfiguration::sampling_rate=line_list->at(0).toDouble();
but new error came qualified-id decalration before "=" token

[jsulm]

@thippu said in How to define static members in a static function in .cpp file?:

double AmpConfiguration::sampling_rate=line_list->at(0).toDouble();

Please read again what I wrote.
Where do you call this now?
It looks like you're now trying to declare a LOCAL variable with same name which is for sure not what you want to do.

[thippu]

@jsulm said in How to define static members in a static function in .cpp file?:

Where do you call this now?

In the mainwindow.cpp

[jsulm]

@thippu said in How to define static members in a static function in .cpp file?:

In the mainwindow.cpp

WHERE EXACTLY?

[thippu]

@jsulm
In the constructor of mainwindow.cpp
I'm calling AmpConfiguration::ReadIni(); First statement itself

[jsulm]

@thippu Can you actually be more precise when answering questions?
Do you mean you put that line in the constructor or inside ReadIni()?
But as I said: you're declaring a local variable with same name.
It must be like this:

AmpConfiguration::sampling_rate=line_list->at(0).toDouble();

AmpConfiguration:: can be removed as well...

[thippu]

@jsulm said in How to define static members in a static function in .cpp file?:

local variable

I would like it to be a global static variable.

and I would like to use it(initialize) inside AmpConfiguration::ReadIni()

@jsulm said in How to define static members in a static function in .cpp file?:

AmpConfiguration::sampling_rate=line_list->at(0).toDouble();

finally, Calling the AmpConfiguration::ReadIni()in constructor of mainwindow.cpp.

[thippu]

@jsulm said in How to define static members in a static function in .cpp file?:

AmpConfiguration::sampling_rate=line_list->at(0).toDouble();

No, change in the error. still, I'm getting undefined reference

[jsulm]

@thippu "I would like it to be a global static variable." - then why do you declare it as local variable?
Did you put

double AmpConfiguration::sampling_rate=10.2; // This has to be OUTSIDE of any method/constructor
void AmpConfiguration::ReadIni()
{
    sampling_rate=line_list->at(0).toDouble();
}

as I already wrote above?
Please read about static members in C++.

[thippu]

@jsulm said in How to define static members in a static function in .cpp file?:

// This has to be OUTSIDE of any method/constructor

Worked. bro
Thank you