Pointer in C:-
A pointer in C is a variable which refers only address. (address is a location in memory).
Pointer is 4byte because an address is a 4 byte long.
Pointer cannot refers any address beyond 4GB of memory in GCC compiler.
APPLICATION OF THE POINTER:-
It is used for dynamic memory allocation and array implementation.
Function pointer implementation.
Array implementation
Direct address and hardware address.
Random access or direct access address of memory variable.
Dangling pointer:-
If a pointer refers unauthenticated address in memory is called dangling pointer.
#include <stdlib.h>
#include <stdio.h>
int main()
{
int *p = (int *)malloc(sizeof(int));
// ptr becomes a dangling pointer
free(p);
p = NULL;
}
Wild pointer:-
If a pointer does not refer any address in memory called wild pointer.
#include <stdio.h>
int main()
{
int *p; // wild pointer
int x = 10;
// p is not a wild pointer now
p = &x;
return 0;
}
Null pointer:-
When the pointer refers the starting address of the memory is zero address is called null pointer.
APPLICATION OF NULL POINTER:-
It represents the last node of a link list.
It represents the stack or queue is empty or not.
It represents heap memory is empty or not.
#include <stdio.h>
int main()
{
// Null Pointer
int * = NULL;
printf("The value of pointer is %u", p);
return 0;
}
D reference:-
Doing write or read operation using pointer the concept is called D reference.
D reference of a dangling pointer and wild pointer became segmentation from.
Generic pointer:-
Pointer to void type is called generic pointer.
Generic pointer can refer any address but it cannot be difference
#include <stdio.h>
main()
{
int x=10;
void *p=&x;
printf(“%d”,*p);
}
APPLICATION OF GENERIC POINTER:-
Generic pointer is suitable to refer incomplete types(the memory is allocated by malloc and calloc )
It is suitable to refer VA-list (VA-list is used as the formal parameter of a function).
Near pointer:-
If a pointer refers address the same segment memory is called near pointer.
Far pointer:-
If a pointer refers address in other segments in memory is called far pointer.