Dynamic memory allocation

memory的管理非常重要。memory也是一种resource，与本文相关的有：

• RAII
• The-rule-of-three-five-zero

C++: new 和 delete

C: malloc 和 free

wikipedia C dynamic memory allocation

C dynamic memory allocation refers to performing manual memory management for dynamic memory allocation in the C programming language via a group of functions in the C standard library, namely malloc, realloc, calloc and free.[1][2][3]

The C++ programming language includes these functions; however, the operators new and delete provide similar functionality and are recommended by that language's authors.[4] Still, there are several situations in which using new/delete is not applicable, such as garbage collection code or performance-sensitive code, and a combination of malloc and placement new may be required instead of the higher-level new operator.

NOTE: 上面这一段描述，显然比较了new/delete 和 malloc

Many different implementations of the actual memory allocation mechanism, used by malloc, are available. Their performance varies in both execution time and required memory.

alignment的处理

C++、C都对dynamic allocation的alignment进行了要求，它们(大多数情况)都要求保证alignment，显然这简化了programmer的操作、保证了performance。

关于C的dynamic allocation的alignment，参见 malloc 章节。

关于C++的dynamic allocation的alignment，参见 new-operator 章节。