Some weird constructors

[highnergy]

Hi,

I have came across with following constructs a lot. But I couldn't give them a meaning. Please help me understand them.

1. 
   

   void afunction (QString& str) {...};

   void afunction (QString& str) {...};

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   Suppose we have function and and gets a reference to a QString parameter. In order to call that function one has to create a QString object and pass it to the function.
   

   QString obj("Some string");
   afunction(obj);

   QString obj("Some string");
   afunction(obj);

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   But the weird thing is you don't have to create an object. You can just pass a string literal like "This is a Literal" to the function instead of a QString object;
   

   afunction("This is a Literal");

   afunction("This is a Literal");

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   and it works. Why?
2. 
   Apart from sending a string literal to the above function there is also another weird way to call the function.
   

   afunction(QString("Hello there"));

   afunction(QString("Hello there"));

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   Above call works but it shouldn't. How an QString object gets created just by using class name with parantheses? It is not even creates an object. What is the meaning of QString("Hi there") alone in the function parameter list? First of all it is not the way books thought us creating objects. I can create a QString object with two ways that I know.
   

   QString obj = new QString("Hi there"); // This creates object on the heap. 
   QString obj("Hello There"); // Likewise This one creates an object on the stack.

   QString obj = new QString("Hi there"); // This creates object on the heap. 
   QString obj("Hello There"); // Likewise This one creates an object on the stack.

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   I don't know any other way to create an object. Turning back to original subject, How an object gets created just by using it's class name?

regards