Page 82 - Programming Microcontrollers in C

Pointers 67

int able[10];
int *p;
After it has been properly declared, when the name able is invoked
without the square brackets, the name is a pointer to the first location in
the array. So the following two statements are equivalent:

p = &able[0];
and

p = able;
Of course, the nth element of the array may be addressed by

p = &able[n];
The unary pointer operators have higher precedence than the arith­
metic operators. Therefore,

*pi = *pi + 10;
y = *pi + 1;
*pi += 1;

all result in the integers being altered rather than the pointers. In the
first case, the integer pointed to by pi will be increased by 10. In the
second case, y will be replaced by one more than the integer pointed
to by pi. Finally, the integer pointed to by pi will be increased by
1. The statement
++*pi;

causes the integer pointed to by pi to be increased by 1. Both ++
and the unary * associate from right to left, so in the following case
*pi++;

the pointer pi is incremented after the dereference operator is applied.
Therefore, the pointer is incremented in this case, and the integer *pi
remains unaltered. If you wish to post-increment the integer *pi, use
(*pi)++;
At times, it is necessary to pre-increment the pointer before the
dereference. In these cases, use

*++pi;