[Qt-interest] can not copy QString and other non understood other c++ error

[Andreas Pakulat]

On 28.02.10 23:38:28, Matthias Pospiech wrote:
> This code does not compile:
> 
> 
> class TaskPrivate
> {
> public:
>     TaskPrivate(Task * parent)
>         : taskHandle(0)
>         , aiChannels(AIChannels(parent))
>     {}
> 
>     AIChannels aiChannels;
>     TaskHandle taskHandle;
>     QString taskName;
> };
> 
> 
> Task::Task(QObject *parent, QString taskName /* = "" */)
>     :   QObject(parent)    
>     ,   d(new TaskPrivate(this))
> {
>     d->taskName = taskName;
>     TaskHandle & taskHandle = d->taskHandle;
>     int error = DAQmxCreateTask (taskName.toLatin1(), &taskHandle);
> }
> 
> with these errors:
> 
> src\task.cpp: In constructor 
> 'NationalInstruments::DAQ::Task::Task(QObject*, QString)':
> 
> src\task.cpp:31: error: passing 'const QString' as 'this' argument of 
> 'QString& QString::operator=(const QString&)' discards qualifiers

You've made your d-pointer a const object, hence you can't change its
variables, move the const to the other side of the * and read up again
on const-pointer vs. pointer-to-const. 
 
> src\task.cpp:32: error: invalid initialization of reference of type 
> 'void*&' from expression of type 'void* const'

Probably the same source. 

Andreas

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