Question

Provide an overview of memory allocation and the services (allocation and deallocation) provided by the memory manager.

size = 1024 // 1,024 bytes pointer = malloc( size ) // allocate size bytes of memory if pointer is NULL raise_error no_memory // not enough memory! … // use the memory free( pointer ) // release the memory

Answer 1

• There are two ways to assign memory for the program, one is statically allocated memory and other one is dynamically allocated memory.
• Statically allocated memory is the allocated memory location, which can not be changed during the run time of the program, where as the dynamically allocated memory has the advantage of allocating, deallocating and resizing of the memory during the run time of the program.
• For the Dynamic Memory Allocation in the C programing, there four function. malloc(), calloc(), free() and realloc().
• malloc() function is useful for dynamically allocating a large block of the memory with a particular size, the size of memory is passed as an argument to the function. When the function allocates the memory successfully, then it returns the starting address of the memory. If the memory is not allocated due to unavailability of the memory , then function returns NULL pointer.
• calloc() is contiguous allocation of memory, where the dynamic memory is allocate in particular number of blocks. As the memory is allocated, it is initialized with the default value '0'.
• free() function is useful in de-allocation of the memory. Whenever memory allocation occurs using malloc() or calloc() function, then it is not deallocated on its own, it is programmer jobs to deallocate the dynamically allocated memory after its use.
• realloc() function is useful in resizing the dynamically allocated memory.
• Please note that the dynamic memory is allocated from the Heap section of the memory.

Code:

size = 1024

pointer = malloc(size)

free(pointer)

Explanation:

• The size variable is assigned with 1024 value.
• malloc() function allocates the 1024 bytes of memory and store the starting address of the memory in the pointer.
• using the free() function, the dynamically allocated memory is deallocated.