DYNAMIC MEMORY ALLOCATION

DYNAMIC MEMORY ALLOCATION

            The memory allocation may be classified as static memory allocation and dynamic memory allocation.

Static memory allocation:     Memory for the variables is created at the time of compilation is known as static memory.

Dynamic memory allocation:           Memory for the variables is allocated at the time of execution of the program is called dynamic memory.  The following functions are used for dynamic memory allocation which are defined in stdlib.h and alloc.h header files.

            1. malloc()       2. calloc()        3. realloc()       4. free()

malloc(), calloc() and realloc() are memory allocation functions and free() is a memory releasing function.

            The program instructions, global and static variables are stored in a region known as permanent storage area.  Local variables are stored in another region called stack.  The memory spaced located between stack and permanent storage area is available for dynamic memory allocation during execution of the program.  This free memory region is called as heap.