What is the pointer

Pointer

A pointer is a variable that stores the memory address of another variable. In above example ‘ptr’ is a pointer variable because it stores the address of another variable ‘n’. Hence it is called a pointer to n. Since a pointer is a variable, it will also occupy some memory location.

Value of variable ‘n’ can be accessed in two ways:

Using the name of the variable i.e. ‘n’

Using pointer

Reference and De-reference Referencing means taking the address of an existing variable (using &) to set a pointer variable.

The operation of accessing variable using the pointer is called ‘dereference’. For example, accessing variable ‘n’ using ‘ptr’ is called dereference. De-referencing is the operation to access or manipulate data contained in the memory location pointed to by a pointer.

The ‘&’ operator is used for reference. It is also called the ‘address-of ‘operator. The ‘*’ operator is used for dereference. It is also called the ‘value-at’ operator.

Syntax: *pointer

Example:

int n=20;

int *ptr;

ptr = &n; //reference printf(“%d”,*ptr); //deference. Displays 20 Size of a pointer

A pointer is a variable. Hence it occupies some memory. The size of a pointer variable is the same as an unsigned integer (either 2 or 4 bytes).

The size of pointer does not depend on the type of data it points to.

sizeof()operator can be used to find out the size of a pointer variable as shown below: Example:

float *ptr;

printf(“The size of ptr is %d”, sizeof(ptr));

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