How can one encourage his (older) compiler , C/C++ Programming

Q: How can one encourage his (older) compiler to check new to see automatically if it returns

NULL?      

A: His compiler eventually will.

If he contain an old compiler which doesn't auto magically perform the NULL test, he might force the runtime system to do the test through installing a "new handler" function. his "new handler" function might do anything he wish, such as throw an exception, delete some of the objects and return (wherein case operator new will retry the allocation), print a message & abort() the program, etc.

Here's a sample "new handler" which prints a message & throws an exception. The handler is installed by using std::set_new_handler():

#include // To obatin std::set_new_handler

#include // To obtain abort()

#include // To obtain std::cerr

class alloc_error : public std::exception {

public:

alloc_error() : exception() { }

};

void myNewHandler()

{

// this is own handler. It can do anything he wants. throw alloc_error();

}

int main()

{

std::set_new_handler(myNewHandler); // Install "new handler"

...

}

After the std::set_new_handler() line is executed, operator new will call your myNewHandler()

If it run out of memory. It means that new will never return NULL:

Fred* p = new Fred(); // No require to check if p is NULL

Note: If your compiler doesn't support exception handling, you can, as a final resort, change the line throw ...; to:

std::cerr << "try to allocate memory failed!" << std::endl;

abort();

Note: If some global/static object's constructor use new, this won't employ the myNewHandler() function since that constructor will get called before main() starts. Unluckily there's no convenient method to guarantee that the std::set_new_handler() will be called before the first use of new. For instance, even if you put the std::set_new_handler() call in the constructor of global object, still you don't know if the module ("compilation unit") which contains that global object will be elaborated in initial or in last or somewhere in between. Thus you still don't have any guarantee that your call of std::set_new_handler() will happen before any other global's constructor gets invoked.

Posted Date: 3/19/2013 8:39:36 AM | Location : United States







Related Discussions:- How can one encourage his (older) compiler , Assignment Help, Ask Question on How can one encourage his (older) compiler , Get Answer, Expert's Help, How can one encourage his (older) compiler Discussions

Write discussion on How can one encourage his (older) compiler
Your posts are moderated
Related Questions
Using a Friend Using a friend function is quite easy. The following example explains a friend function to access members of two classes. class Bclass;

A palindrome is a string that reads the same from both the ends. Given a string S convert it to a palindrome by doing character replacement. Your task is to convert S to palindrome

There are ''''n'''' ants on a ''''n+1'''' length rod. The ants are numbered from 1 to n and are initially placed at positions starting from position 1 till position n. They are mov

Q: But MFC appear to encourage the employ of catch-by-pointer; should I do the similar? A: Depends. If you're utilizing MFC and catching one of their exceptions, by all means, d


find the minimum total number of shelves

#question.College life is tough. Eating pizza for every meal is hitting you hard. You are looking at working out to stay healthy. You found a web site that tells you how many ca

Write a program to find the area under the curve y = f(x) between x = a and x = b, integrate y = f(x) between the limits of a and b

Define a procedure that takes three numbers as arguments and returns the sum of the squares of the two larger numbers.

What happens while a derived-class object is developed & destroyed? A: Space is allocated (on the heap or the stack) for the full object (i.e. adequate space to store the data m