how to modify functionality of new operator ?

[whizaard]

I am writing a program in C++ which has a requirement that:
new operator should return a NULL if it is unable to allocate memory, instaed of throwing an exception and exiting.
How can i acieve this ??????

[dmjpro]

I am writing a program in C++ which has a requirement that:
new operator should return a NULL if it is unable to allocate memory, instaed of throwing an exception and exiting.
How can i acieve this ??????

Welcome to TSDN.

Do u know operator overloading?
And if you know remember one thing the new operator can be overloaded.

void * operator new(int size)
{
//your code goes here.
}
//it may be something like that, right now i can't remember.
 

Kind regards,
Dmjpro.

[weaknessforcats]

I am writing a program in C++ which has a requirement that:
new operator should return a NULL if it is unable to allocate memory, instaed of throwing an exception and exiting.
How can i acieve this ??????

Why???

When you run out of memory, new throws a bad_alloc exception. At that time there will be just enough memory to create the exception.

In the case of Windoows, 3 hours before bad_alloc is thrown a message appears:

Windows running low on resources....


2 hours before bad_alloc is thrown, an hourglass apprears briefly when you allocate memory.

1 hour before bad_alloc is thrown, the hourglass appears for 2 seconds

30 minutes before bad_alloc is thrown, the hourglass appears for 1 minute each time you allocate.

15 minutes before bad_alloc is thrown, you notice the disc access light blinking

5 minutes before bad_alloc is thrown, the hourglass is on for 10 minutes each time you allocate and your PC is vibrating across the floor dues to the disc accesses.

1 minute before bad_alloc is thrown, your hard drive crashes from over use.

For Windows, this means your bad_alloc will never be thrown. That means you have no chance to reach in and re-engineer memory management.

[JosAH]

That doesn't happen on my old Sun pizza boxes ...

kind regards,

Jos ;-)

[Savage]

I am writing a program in C++ which has a requirement that:
new operator should return a NULL if it is unable to allocate memory, instaed of throwing an exception and exiting.
How can i acieve this ??????

You could use no_throw new (new(no_throw) ) and then handle allocation problems all by yourself.

The question is:Why do you want to do that?

Do you want to speed up your program by evading exception handling,or is it something else?

[RRick]

Overloading the new operator is a topic that has shown up before, but one question remains.

How do you overload the global new and still be able to call the "original" global new thats being overloaded? It seems like we should have a recursive call to the "newer" new and never access the "original" new.

[weaknessforcats]

You don't overload the new operator. What you overload is the function operator new(). The new operator calls operator new().

You need to avoid hiding the global operator new().

Check out Effective C++ by Scott Meyers Items 8 and 9.