set_new_handler
Sets the function to be called when a request for memory allocation cannot be satisfied.
Defined in header <new.h>
Syntax
#include <new.h>
void (* set_new_handler(void (* myJiandler){)))();Portability
| DOS | UNIX | Windows | ANSI C | C++ only |
|---|---|---|---|---|
| ■ | ■ | ■ | ■ |
Remarks
set_new_handler sets the function to be called when operator new cannot allocate the requested memory. By default operator new will return zero if it cannot allocate memory. You can affect this default behavior by setting a new handler and calling set_new_handler.
If new cannot allocate the requested memory it calls the handler that was set by a previous call to set_new_handler. my_handler should specify the actions to be taken when new cannot satisfy a request for memory allocation. If myjiandler returns, then new will again attempt to satisfy the request.
Ideally, myjiandler would free up memory and return, new would then be able to satisfy the request and the program would continue. However, if myjiandler cannot provide memory for new, myjiandler must terminate the program. Otherwise, an infinite loop will be created.
The default handler is reset by set_new_handler(0).
Preferably, you should overload the operator new() to take appropriate actions for your applications.
Return value
set_new_handler returns the old handler, if it has been defined. By default, no handler is installed.
The user-defined argument function, myjiandler, should not return a value.
See also
newjiandler
Example
#include <iostream.h>
finclude <new.h>
#include <stdlib.h>
void mem_warn() {
cerr << "\nCannot allocate!";
exit(l);
}
void main(void) {
set_new_handler (mem_warn);
char *ptr = new char[100];
cout << "\nFirst allocation: ptr = " << hex << long(ptr);
ptr = new char [64000U];
cout << "\nFinal allocation: ptr = " << hex << long(ptr);
set_new_handler (0); // Reset to default.
}
Program output
First allocation: ptr = 283e0f30
Cannot allocate!Differences from modern implementations
Nothing recorded yet.
Modern references
These are search links, not yet checked by hand.
Extraction notes
- heading `set new handler` read as `set_new_handler`
Stable link: /3.1/new.h/set_new_handler/
· short form /3.1/set_new_handler/