Default Value for qmap optional parameter

Question

I'm working in C++ and want to create a function with an optional parameter that is a QMap. The question is what do I set the default value to. I want it to be an empty map.

void function(int i, QMap< QString, QString > MyMap = ???)

what do you put for ???

Answer 1

Question:

what do you put for ???

1. You can put a default constructed object.

   void function(int i, QMap< QString, QString > MyMap = QMap<QString, QString>())
   

2. You can put a call to a function that returns a compatible object.

   QMap< QString, QString > const& foo();
   void function(int i, QMap< QString, QString > MyMap = foo())
   

Answer 2

You can use a pointer to QMap (QMap*) and give it the NULL value as default:

void function(int i, QMap< QString, QString > *MyMap = NULL)
{

}