How to read pointers

Vijay Nerkar — Tue, 05 Apr 2022 06:47:31 +0000

Hi all,
This is my first post. Many peoples have problems on pointers.
This post will help to understand pointers.

char a;
Read : 'a' is a variable of char type.
char *ptr;
Read : 'ptr' is a pointer to char.
char* ptr[5];
Read : 'ptr' is an array of 5 pointers to a char.
Note : The precedence rules say that the square brackets([]) are higher than the asterisk(*).
Ex:
int *ptr1 = NULL;
int *ptr2 = NULL;
int *ptr3 = NULL;
int *ptr4 = NULL;
int *ptr5 = NULL;
char *ptr[5] = {ptr1, ptr2, ptr3, ptr4, ptr5};
int ** ptr2;
Read : 'ptr2' is a pointer to pointer to int
Ex:

int a = 4;
int *ptr1 = &a;
int **ptr2 = &ptr1;

cout << "\n a : " << a;
cout << "\n Address of a : " << &a;
cout << "\n ptr1 : " << ptr1;
cout << "\n *ptr1 : " << *ptr1;
cout << "\n ptr2 : " << ptr2;
cout << "\n *ptr2 : " << *ptr2;
cout << "\n **ptr2 : " << **ptr2;

Output:

a : 4
Address of a : 0040F8D0
ptr1 : 0040F8D0
*ptr1 : 4
ptr2 : 0040F8C4
*ptr2 : 0040F8D0
**ptr2 : 4

const int *ptr; Read : 'ptr' is a pointer to const int Ex: const int a = 4; const int *ptr = &a;

cout << "\n a : " << a;
cout << "\n Address of a : " << &a;
cout << "\n ptr : " << ptr;
cout << "\n *ptr : " << *ptr;

Output:

a : 4
Address of a : 0040F8D0
ptr : 0040F8D0
*ptr : 4

const int **ptr2; Read : 'ptr2' is a pointer to pointer to const int Ex: const int a = 4; const int *ptr1 = &a; const int **ptr2 = &ptr1;

Output:

a : 4
Address of a : 0040F8D0
ptr1 : 0040F8D0
*ptr1 : 4
ptr2 : 0040F8C4
*ptr2 : 0040F8D0
**ptr2 : 4

char * const * ptr2; Read : ptr2 is a pointer to const pointer to char Ex: char a = 'x'; char *const ptr1 = &a; char * const * ptr2 = &ptr1;

Output:

a : x
Address of a : 0040F8D0
ptr1 : 0040F8D0
*ptr1 : x
ptr2 : 0040F8C4
*ptr2 : 0040F8D0
**ptr2 : x

const int * const * ptr2; Read : ptr2 is a pointer to const pointer to const int Ex: const int a = 10; const int * ptr1 = &a; const int * const * ptr2 = &ptr1;

printf("\n a : %d ", a);
printf("\n Address of a : %d ", &a);
printf("\n ptr1 : %d ", ptr1);
printf("\n ptr1 : %d ", ptr1);
printf("\n ptr2 : %d ", ptr2);
printf("\n *ptr2 : %d ", *ptr2);
printf("\n **ptr2 : %d ", **ptr2);