全局运算符new和malloc之间的差异 [英] Difference between global operator new and malloc

问题描述

C ++有几个函数来获取动态存储，其中大多数在一些基本方面有所不同。通常由操作系统添加几个。

C++ has several functions to acquire dynamic storage, most of which differ in some fundamental way. Several more are usually added by the OS.

其中两个由于其可移植性和相似性而特别感兴趣： malloc 和 :: operator new 。

Two of these are of special interest due to their portability and similarity: malloc and ::operator new.

全局 void * operator new（size_t，:: std :: nothrow&）和 void * malloc（size_t）？

由于我所说的似乎有些混乱，请考虑以下两个调用：

Since there seems to be some confusion what I am talking about, consider the following two calls:

void* p = ::std::malloc(10);
void* q = ::operator new(10, ::std::nothrow);

显而易见的和微不足道的区别是如何释放内存：

The obvious and trivial difference is how to deallocate the memory:

::std::free(p);
::operator delete(q);

注意：此问题不是 new / delete和malloc / free之间的区别是什么？，因为它谈到使用全局 运算符新，实际上不执行任何ctor调用。

Note: This question is not a duplicate of e.g. What is the difference between new/delete and malloc/free? since it talks about using the global operator new that does not actually perform any ctor calls.

推荐答案

除了语法和自由与 / code>，

The main differences, aside from syntax and free vs. delete, are

1. 您可以轻松地 replace :: operator new ;


2. malloc 附带 realloc ，其中新没有等效项;


3. new 的概念是 new_handler ，因为没有等于malloc 。

1. you can portably replace ::operator new;
2. malloc comes with realloc, for which new has no equivalent;
3. new has the concept of a new_handler, for which there is no malloc equivalent.

（替换 malloc 打开蠕虫病毒。它可以做，但不可移植，因为它需要链接器的知识。）

(Replacing malloc opens up a can of worms. It can be done, but not portably, because it requires knowledge of the linker.)

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