Pointer
Arithmetic
Pointer variables can also be used
in arithmetic expression like adding and subtracting integer variable and
manipulation from a pointer variable through the resulting expression.
Different operations perform on
pointer are as under:
1. Pointers can be incremented or
decremented to point to different location.
Ex,
int x=20;
int *ptr=&x;
ptr++
ptr—
here, ptr is a pointer to integer
with address of variable x , if ptr has value 65526 then after the operation
ptr++ (ptr=ptr+1) , the value of ptr would be 65528. Increment and decrement in pointer value is
based upon the size of data type that it points to.
2.if ptr1 and ptr2 are properly
declared and initialized pointers the following operations are valid
Ex,
ans=ans+ *ptr1;
*ptr1 = *ptr2 +5;
multi= *ptr1 * *ptr2;
3. When two pointers point to the
same datatype , they can be compared using relational operators
Ex,
ptr1==ptr2
ptr1<ptr2
These comparisons are common in
handling arrays.
4. A pointer variable can be
assigned the value of another variable.
Ex, ptr1=&x;
5. A pointer variable can be
assigned the value of another pointer
variable.
Ex, ptr1=ptr2;
Here both the pointer points to the object of same data type.
6. A pointer variable can be
assigned with NULL or zero value.
Ex,
ptr=null;
7. Two pointer variable can not be
added
Ex,
ptr1=ptr1+ptr2;
1. A pointer variable can
not be multiplied or divided with a constant.
Ex,
ptr1/5
2. A value can not be
assigned to an arbitrary address
Ex,
&ptr=100;
Example:
#include<stdio.h>
#include<conio.h>
void
main()
{
int *ptr1,*ptr2;
int a,b,x,y,z;
clrscr();
a=30;b=6;
ptr1=&a;
ptr2=&b;
x=*ptr1+ *ptr2-6;
y=(6 * *ptr1) / (*ptr2 +30);
printf("\n a-> value = %d Address =
%u",x,ptr1);
printf("\n b-> value = %d Address =
%u",y,ptr2);
printf("\n x= %d
y=%d",x,y);
*ptr1= *ptr1 + 70;
*ptr2= *ptr1;
printf("\n a=%d, b=%d",a,b);
getch();
}
