Difference between revisions of "cpp/memory/new/set new handler"
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#include <iostream> | #include <iostream> | ||
#include <new> | #include <new> | ||
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void handler() | void handler() | ||
{ | { | ||
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std::set_new_handler(nullptr); | std::set_new_handler(nullptr); | ||
} | } | ||
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int main() | int main() | ||
{ | { | ||
std::set_new_handler(handler); | std::set_new_handler(handler); | ||
try { | try { | ||
| − | while(true) | + | while (true) { |
new int[100000000ul]; | new int[100000000ul]; | ||
| − | }catch(const std::bad_alloc& e) { | + | } |
| + | } catch (const std::bad_alloc& e) { | ||
std::cout << e.what() << '\n'; | std::cout << e.what() << '\n'; | ||
} | } | ||
Revision as of 10:45, 23 September 2013
| Defined in header <new>
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| std::new_handler set_new_handler( std::new_handler new_p ) |
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Makes new_p the new global new-handler function and returns the previously installed new-handler.
The new-handler function is the function called by allocation functions whenever a memory allocation attempt fails. Its intended purpose is one of three things:
The default implementation throws std::bad_alloc. The user can install his own new-handler, which may offer behavior different than the default one.
If new-handler returns, the allocation function repeats the previously-failed allocation attempt and calls the new-handler again if the allocation fails again. To end the loop, new-handler may call std::set_new_handler(nullptr): if, after a failed allocation attempt, allocation function finds that std::get_new_handler returns a null pointer value, it will throw std::bad_alloc.
At program startup, new-handler is a null pointer.
Contents |
Parameters
| new_p | - | pointer to function of type std::new_handler, or null pointer |
Return value
The previously-installed new handler, or a null pointer value if none was installed.
Exceptions
| (none) | (until C++11) |
| noexcept specification: noexcept |
(since C++11) |
Example
#include <iostream> #include <new> void handler() { std::cout << "Memory allocation failed, terminating\n"; std::set_new_handler(nullptr); } int main() { std::set_new_handler(handler); try { while (true) { new int[100000000ul]; } } catch (const std::bad_alloc& e) { std::cout << e.what() << '\n'; } }
Output:
Memory allocation failed, terminating std::bad_alloc
See also
| allocation functions (function) | |
| set_new_handler |
registers a new handler (function) |
| function pointer type of the new handler (typedef) | |
| exception thrown when memory allocation fails (class) |
