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The C programming language manages memory statically, automatically, or dynamically.Static-duration variables are allocated in main memory, usually along with the executable code of the program, and persist for the lifetime of the program; automatic-duration variables are allocated on the stack and come and go as functions are called and return.
In many languages, global variables are always static, but in some languages they are dynamic, while local variables are generally automatic, but may be static. In general, static memory allocation is the allocation of memory at compile time, before the associated program is executed, unlike dynamic memory allocation or automatic memory ...
Memory management (also dynamic memory management, dynamic storage allocation, or dynamic memory allocation) is a form of resource management applied to computer memory.The essential requirement of memory management is to provide ways to dynamically allocate portions of memory to programs at their request, and free it for reuse when no longer needed.
A free list (or freelist) is a data structure used in a scheme for dynamic memory allocation. It operates by connecting unallocated regions of memory together in a linked list, using the first word of each unallocated region as a pointer to the next. It is most suitable for allocating from a memory pool, where all objects have the same size.
However dynamic memory must be repeatedly refreshed with a surge of current dozens of time per second, or the stored data will decay and be lost. Flash memory allows for long-term storage over a period of years, but it is much slower than dynamic memory, and the static memory storage cells wear out with frequent use.
Paged allocation divides the computer's primary memory into fixed-size units called page frames, and the program's virtual address space into pages of the same size. The hardware memory management unit maps pages to frames. The physical memory can be allocated on a page basis while the address space appears contiguous.
The static/dynamic terminology used to refer to combinatorial circuits is related to the use of the same adjectives used to distinguish memory devices, e.g. static RAM from dynamic RAM, in that dynamic RAM stores state dynamically as voltages on capacitances, which must be periodically refreshed. But there are also differences in usage; the ...
Programmers may further choose to explicitly use the stack to store local data of variable length. If a region of memory lies on the thread's stack, that memory is said to have been allocated on the stack, i.e. stack-based memory allocation (SBMA). This is contrasted with a heap-based memory allocation (HBMA).