C - POINTER
Address of memory location
- Within computer's memory , every data occupies some memory location . The number of memory location required to store a data depends upon
type of data (i.e. datatype)
- for example, a single character will typically be stored in 1 byte(8 bits) of memory,an integer usually requires 2 bytes(16 bits).
A floating variable may require 4 bytes(32 bits) and a Double may require 8 bytes.
- Suppose v is a variable that represent some particular data item . The compiler will automatically assign some memory location for this data item.
- The data item can be access if we know the location of The first memory location.Adjacent memory locations within a computers are numbered consecutively from beginning to end of memory area.The numbers associated with each memory location is known as memory location's address.
- Most computer use hexadecimal number to designate the addresses of consecutive memory locations,though some computers use octal numbering system.
- The address of variable x can be determined by expression &x, where '&' is unary operator called address operator , which evaluates address of
- A pointer is variable that stores memory address of other variables.
- It does not contain any integer, float , character or double value but contains merely address of some variable.
DECLARATION OF POINTER
- Like other variable pointer variable must be declared before they can be used in a C program.
- When pointer variable is declared,the variable name must be preceded by by an asterisk (*).
- The datatype appears in declaration refers to the variable to whom the pointer points rather the the pointer itself.
- Thus, a pointer declaration may be written in general terms as ;
here datatype depends on the factor that pointer is pointing to variable of which datatype.
declares that pv and px as pointers which can point to variables of datatype int i.e. they can store address of variables of datatype int.