According to these guidelines, we can write:
pa = &a[4];
// pa points to a[4]
x = *(pa + 3);
// x = a[7]
y = *pa + 3;
// y = a[4] + 3
Also, you need to be careful with operator precedence:
*pa++;
// is equal to *(pa++), increments the pointer!
(*pa)++;
// increments the pointed object!
Following examples are also valid, but better avoid this syntax as it can make the
code
really
illegible:
(a + 1)[i] = 3;
// same as: *((a + 1) + i) = 3, i.e. a[i + 1] = 3
(i + 2)[a] = 0;
// same as: *((i + 2) + a) = 0, i.e. a[i + 2] = 0
Assignment and Comparison
You can use a simple assignment operator (
=
) to assign value of one pointer to
another if they are of the same type. If they are of different types, you must use a
typecast operator. Explicit type conversion is not necessary if one of the pointers is
generic (of
void
type).
Assigning the integer constant 0 to a pointer assigns a null pointer value to it. The
mnemonic
NULL
(defined in the standard library header files, such as
stdio.h
)
can be used for legibility.
Two pointers pointing into the same array may be compared by using relational
operators
==
,
!=
,
<
,
<=
,
>
, and
>=
. Results of these operations are same as if they
were used on subscript values of array elements in question:
int
*pa = &a[4], *pb = &a[2];
if
(pa > pb) { ...
// this will be executed as 4 is greater than 2
}
MikroElektronika: Development tools - Books - Compilers
71
page
mikroC - C Compiler for Microchip PIC microcontrollers
mikroC
making it simple...
