Introduction:
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Pointer is a derived data type in C. It is built from the
one of the fundamental data type available in C.
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A pointer is a variable that points to or references a
memory location in which data is stored.
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Each memory cell in the computer has an address that can
be used to access that location so a pointer variable points to a memory
location(address). It can be used for different purpose such as access the
variable value at that address , to increment it to get address of next element
and change the contents of this memory location via the pointer.
Pointer declaration:
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In C variable must be declared for its use. The poiner
variable must be declared before it is used. A pointer is a variable that
contains the memory location(address) of another variable.
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The syntax is as shown below.
type * variable_name ;
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According to the above syntax type specifying the type of data stored in the location identified
by the pointer. The asterisk(*)
tells the compiler that variable_name
is a pointer variable. variable_name is the name of the
variable.
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The unary operator * is called indirection or
dereferencing operator,
Ex,
int *ptr;
char *string;
Address operator:
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Once declare a pointer variable must be need to point it
to something it can be done by assigning to the pointer the address of
the variable.
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The unary operator & called address of operator is
used to assign the address of variable.
Ex, int num=10;
int *ptr; //
Declaration
ptr=# // Initialization
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This places the address where num is stores into the
variable ptr. If num is stored in memory 212 address then the variable ptr has
the value 21260.
/* A program to
illustrate pointer declaration*/
void main()
{
int *ptr;
int sum;
sum=45;
ptr=∑
printf (“\n Sum is %d \n”, sum);
printf (“\n The address of sum is = %u”, ptr);
void main()
{
int *ptr;
int sum;
sum=45;
ptr=∑
printf (“\n Sum is %d \n”, sum);
printf (“\n The address of sum is = %u”, ptr);
printf(“\n value of sum is =
%d”,*ptr);
}
}
