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
how to create database of faculty database......... send me with program

Project Description: I play this game called mobstar (mobstar) and I would like the program to grade my account for me. It would require doing a crime, GTA, jail busting, lead a

padovan string generation till 40

Aim: To implement a program for dynamic data structure(linked list). Code:                       class node {             int data;             node *next;


program to find if a no . is prime or not

Question : (a) One of the most common sorting techniques we have in programming is the ‘Bubble Sort'. This technique will be used to sort an array of elements in ascending or

T o k e n :  Tokens  are  small  entities  in  a  program.    Example: identifiers,  keywords,  constants, operators, strings, etc.  These tokens are used almost in same wa


Conversion between Objects of Different Classes As the compiler does not know anything about the user-defined type, the conversion instructions are to be specified in a functio