如何称呼原来的“operator new”？如果我超载了呢？
假设我需要重载全局 ::operator new() 用于为每个分配的对象存储额外的数据。所以基本上它会这样工作：
- 对于每次调用全局
::operator new()，它将获取传递的对象大小并添加额外数据的大小， - 它将分配一个内存块< /em> 的大小在上一步中推导出来，
- 它将把指针偏移到块中未被额外数据占用的部分，并将该偏移值返回给调用者
::operator delete() 将执行相同的操作相反 - 移动指针、访问额外数据、释放内存。
现在的问题是如何分配内存？当然，我可以调用 malloc() 或一些特定于平台的函数（通常是这样做的）。但通常当我需要在 C++ 中分配原始内存时，我会调用 ::operator new()。我可以调用原始的 ::operator new() 从重载的全局 ::operator new() 内部进行内存分配吗？
Suppose I need to overload global ::operator new() for storing extra data with each allocated object. So basically it would work this way:
- for each call to global
::operator new()it will take the object size passed and add the size of extra data - it will allocate a memory block of size deduced at previous step
- it will offset the pointer to the part of the block not occupied with extra data and return that offset value to the caller
::operator delete() will do the same in reverse - shift the pointer, access extra data, deallocate memory.
Now the question is how do I allocate memory? Of course I can call malloc() or some platform-specific function (that's how it is usually done). But normally when I need to allocate raw memory in C++ I call ::operator new(). Can I call the original ::operator new() to do the memory allocation from inside my overloaded global ::operator new()?
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您无法访问它们，因为它并不是真正的超载，而是替换。当您定义自己的
::operator new时，旧的就会消失。差不多就是这样了。本质上，您需要从自定义
::operator new调用malloc。不仅如此，还要按照18.4.1.1/4中的指示正确处理错误：You can't access them because it isn't really overloading, it's replacement. When you define your own
::operator new, the old one goes away. That's pretty much that.Essentially, you need to call
mallocfrom a custom::operator new. Not only that, but also follow the directions in 18.4.1.1/4 to properly handle errors: