In p = new fred(), does the fred memory "leak" if fred , C/C++ Programming

Q: In p = new Fred(), does the Fred memory "leak" if  Fred constructor throws an exception?

A: No.        

If an exception take place during the Fred constructor of p = new Fred(), the C++ language guarantees that the memory sizeof(Fred) bytes which were allocated will auto magically be released back to the heap.

Here the details: new Fred() is a two-step procedure:

sizeof(Fred) bytes of memory are allocated via the primitive void* operator new(size_t nbytes). This primitive is alike in spirit to malloc(size_t nbytes). (Note, though, that these two are not interchangeable; for example there is no guarantee that the two memory allocation primitives even employ the same heap!).

It develops an object in that memory by calling the Fred constructor. The pointer returned from the primary step is passed as the this parameter to the constructor. This step is wrapped out in a try catch block to manage the case while an exception is thrown during this step.

Therefore the real generated code is functionally similar to:

// Original code: Fred* p = new Fred();

Fred* p = (Fred*) operator new(sizeof(Fred));

try {

new(p) Fred(); // Placement new

}

catch (...) {

operator delete(p); // Deallocate memory throw; // Re-throw exception

}

The statement marked "Placement new" calls the Fred constructor. Inside the constructor the pointer p becomes the this pointer, Fred::Fred().

 

Posted Date: 3/19/2013 8:41:37 AM | Location : United States







Related Discussions:- In p = new fred(), does the fred memory "leak" if fred , Assignment Help, Ask Question on In p = new fred(), does the fred memory "leak" if fred , Get Answer, Expert's Help, In p = new fred(), does the fred memory "leak" if fred Discussions

Write discussion on In p = new fred(), does the fred memory "leak" if fred
Your posts are moderated
Related Questions
Write a C program to input five numbers and print them out on a new line Write a C program to input three real numbers and print them out as follows:   The first variable is

please provide me the assignment help. What is the difference between a copy constructor and an overloaded assignment operator?

Need Payment Gateway Integration Expert Project Description: I am seeking for expert payment gateway integration. You must have done or have experience with integrating me

Program is to swap the two values which are enter by user: Program is to swap the two values which are enter by user through the function with values changed using pointers

Static Member Functions All the objects of the class share static data members of a class. The example above demonstrates how to keep track of all the objects of a class which

Are comments included during compilation stage and placed in EXE file as well? - No, comments encountered by compiler are disregarded. - Their only purpose is ease and guida


traffic light t junction I have 21 LEDs will 6 in each side 3 for the cars the other 3 will be for the people across the street this will be for each side and the last 3 for show

what is binary heap ? what is the c code for the implementation for the binary heap

programme for time table in c++