Dynamic memory allocation

Question 1

types of memory in c

Answer 1

static memory
dynamic memory

Question 2

Dynamic memory allocation

Answer 2

it is a way to allocate memory to a datastructure during the runtime

Question 3

Functions used for DMA

Answer 3

-malloc()-memory allocation
-calloc()-continous allocation
-free()
-realloc()-re allocation

Question 4

malloc()

Answer 4

takes a number of bytes to be allocated and returns a pointer of type void

ptr=(int) malloc(5sizeof(int));-here void pointer is typecasted into int pointer

have to include <stdlib.h> library</stdlib.h>

if the give memory size is out of your systems capability then the malloc returns null to the pointer

ptr[0]=1;
ptr[1]=2;
ptr[2]=3;

Question 5

calloc()

Answer 5

continuous allocation

-initializes with 0
ptr=(int*) calloc(5,sizeof(int));

Question 6

free()

Answer 6

-we use it to free memory that is allocated using malloc and calloc

when a variable(int) is statically allocated then after its use then the memory is freed up automatically which is not in dynamic memory

free(ptr);

Question 7

realloc()

Answer 7

reallocate the (increase of decrease ) the memory using the same pointer and size

ptr=realloc(ptr,newsize);

we cannot do this with array only with dynamically allocated memory