Problem with QMap

cristiano.narcisi

Hi all. I am using the class in the snippet below to pass several parameters to a function

#ifndef CST2220CONFIGPARAMETERMAP_H
#define CST2220CONFIGPARAMETERMAP_H

#include <QMap>
#include <QString>
#include <QDebug>

#define MAC_KEY             "mac"
#define IP_KEY              "ip"
#define CST2220_APK_KEY     "cst2220apk"
#define BWS_APK_KEY         "bwsapk"
#define VIDEX_FOLDER_KEY    "videx_folder"

class Cst2220ConfigParameterMap : public QMap<const char *,QString>
{
public:
    Cst2220ConfigParameterMap(  QString mac,
                                QString ip,
                                QString cst2220_apk_path,
                                QString bws_apk_path,
                                QString videx_folder_path);
};

#endif // CST2220CONFIGPARAMETERMAP_H

I have a strange problem. I can retry the key-value pair only within the constructor and not from outside.

if( this->contains(MAC_KEY))...

return true.

     Cst2220ConfigParameterMap par(mMacAddrMan->getMac(),mIpAddrMan->getIp(),pathCST2220Apk,pathBWSApk,pathVidexFolderApk);

     if( par.contains(MAC_KEY))

returns false!!!!

What am i doing wrong?

I'm getting crazy!

thank you for helping me

Cristiano Narcisi

mrjj

@cristiano.narcisi said:

QMap

Hi
can you show the cpp of the constructor also?
How you add the items.

Inheriting from Qmap is a bit funky for me as with STL that was normally
not super idea. but i dont know with QList. :)

cristiano.narcisi

thanks @mrjj

here the constructor

Cst2220ConfigParameterMap::Cst2220ConfigParameterMap( QString mac,
QString ip,
QString cst2220_apk_path,
QString bws_apk_path,
QString videx_folder_path) : QMap(){

this->insert(MAC_KEY,mac);
this->insert(IP_KEY,ip);
this->insert(CST2220_APK_KEY,cst2220_apk_path);
this->insert(BWS_APK_KEY,bws_apk_path);
this->insert(VIDEX_FOLDER_KEY,videx_folder_path);

}

mrjj

Ok, it does look perfect valid.

have you tried
qDebug() << size(); (in ctor)
and
qDebug() << par.size(); (right after u define par)

cristiano.narcisi

Ok. But what does it happen when the function is contains(..key..)?

mrjj

@cristiano.narcisi
it looks like outside of constructor the key list is no more.
i wanted to see if it says
zero for par.

cristiano.narcisi

@mrjj

Ok but it is very strange. I give you another information: i can view all the key-value pair stored into the par variable using the watches of the editor!!!!

mrjj

@cristiano.narcisi
OK ?!?! That also pretty strange.

what about size inside and out?

cristiano.narcisi

@mrjj

Size outside the ctor is correct. It is 5!!!

cristiano.narcisi

Using the iteartor i can view all the values stored in the QMap .... Probably i don't understand something of very important about how QMap acceses the data.
//your code here

 QMap<const char *, QString>::ConstIterator ii;
 for( ii = par.constBegin(); ii != par.constEnd(); ++ii )
   qDebug() << ii.key() << " = " << ii.value();```

mrjj

@cristiano.narcisi
ok ?!?

I think you should try dump the list using par to see if key corruption
else there is no reason contains should not work.

cristiano.narcisi

@mrjj

Probably i have understood why i can retry the key. The problem is that i am using

QMap< const char *, QString>

This means that the key is a POINTER and not the text !!!

I have replaced the QMap template with

QMap< QString, QString>

Now the key is an ITEM and not a POINTER and i can find all the keys and the value stored within the QMap.

Sorry for bothering you

Thanks for hepling me

Regards

Cristiano Narcisi

kshegunov

@mrjj

Inheriting from Qmap is a bit funky

It's specially noted in the docs that deriving from a container specialization is not recommended. That's probably what seems funky ;)

mrjj

@cristiano.narcisi
ok so
#define MAC_KEY "mac"
used as key did funky stuff?

good found :)

kshegunov

@mrjj said:

used as key did funky stuff?

The only funky stuff with that macro is that char * doesn't have a meaningful operator <, which is required for it to be a key in the map. The comparison is done as you'd compare integers.