set_new_handler用法

原型：_PNH _set_new_handler( _PNH pNewHandler );

 

MSDN解释：Transfer control to your error-handling mechanism if the new operator fails to allocate memory.

如果new操作符分配内存失败，则转向_set_new_handler所指定的错误处理机制中去处理。

 

实例：In this example, when the allocation fails, control is transferred to MyNewHandler.

The argument passed to MyNewHandler is the number of bytes requested.

The value returned from MyNewHandler is a flag indicating whether allocation should be retried:

a nonzero value indicates that allocation should be retried, and a zero value indicates that allocation has failed.

 

当内存分配失败的时候，调用MyNewHandler. 传递给MyNewHandler的参数是需要的bytes字节数.

而MyNewHandler得返回值代表内存分配是否需要被重新调用。

如果返回0，则表示告诉new操作符分配内存失败；

返回非0，则表示告诉new操作符继续尝试分配内存。

 

#include <stdio.h>#include <new.h>#define BIG_NUMBER 0x1fffffffint coalesced = 0;int CoalesceHeap(){   coalesced = 1;  // Flag RecurseAlloc to stop    // do some work to free memory   return 0; //表明分配内存失败，程序退出，如果return 1的程序不断的再重新分配内存}// Define a function to be called if new fails to allocate memory.int MyNewHandler( size_t size ){   printf("Allocation failed. Coalescing heap./n");   // Call a function to recover some heap space.   return CoalesceHeap();}int RecurseAlloc() {   int *pi = new int[BIG_NUMBER];   if (!coalesced)      RecurseAlloc();   return 0;}int main(){   // Set the failure handler for new to be MyNewHandler.   _set_new_handler( MyNewHandler );   RecurseAlloc();}