Pointer in c

What is a pointer?
Pointer is a kind of variable that can hold the address of a
variable. The sign ‘&’ used to refer somethings address and
‘*’ used to refer the value of a pointer variable. ‘%p’, ‘%x’,
‘%X’, ‘%u’ are the format specifier of pointer.

address
content
address
&*pointer

Declaring a pointer variable
General syntax of pointer declaration is,
data-type *pointer_name;
Data type of pointer must be same as the variable, which the
pointer is pointing. void type pointer works with all data
types, but isn't used often.
Example Description
Int* p p is a pointer to an integer.
Int** p p is a pointer to a pointer to an integer.
Int*[] p p is a single-dimensional array of pointers to
integers.
char* p p is a pointer to a char.
void* p p is a pointer to an unknown type.

Initialization of Pointer variable
Pointer Initialization is the process of assigning address of a
variable to pointer variable. Pointer variable contains address
of variable of same data type. In C language address
operator ‘&’ is used to determine the address of a variable.
The ‘&’ returns the address of the variable associated with it.

Pointer variable always points to same type of data.
float a;
int *ptr;
ptr = &a; //ERROR, type mismatch
int a = 10 ;
int *ptr ; //pointer declaration
ptr = &a ; //pointer initialization
or,
int *ptr = &a ; //initialization and declaration together

Dereferencing of Pointer
Once a pointer has been assigned the address of a variable.
To access the value of variable, pointer is dereferenced, using
the indirection operator ‘*’.
int a,*p;
a = 10;
p = &a;
printf("%d",*p); //this will print the value of a.
printf("%d",*&a); //this will also print the value of a.
printf("%u",&a); //this will print the address of a.
printf("%u",p); //this will also print the address of a.
printf("%u",&p); //this will also print the address of p.

Pointer of pointers
A pointer to a pointer is a chain of pointers. Normally, a
pointer contains the address of a variable. A variable that is
a pointer to a pointer must be declared as such. This is
done by placing an additional asterisk in front of its name.
For example, an ‘int’ type pointer to pointer - **p1, ***p2,
****p3 etc.
When we define a pointer to a pointer, the first pointer
contains the address of the second pointer, which points to
the location that contains the actual value as shown below.

Pointer Pointer Variable
Address Address Value
When we define a pointer to a pointer, the first pointer
contains the address of the second pointer, which points to
the location that contains the actual value as shown below.

An example of pointer of pointers

Pointer in c

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Pointer in c