unsigned x[5] = {1, 2, 3, 4, 5};
unsigned sum = 0;
unsigned *p;
unsigned i;

void
csum1()
{
    sum += x[0];
    sum += x[1];
    sum += x[2];
    sum += x[3];
    sum += x[4];
}
void
csum2()
{
    p = x;
    sum += *(p++);
    sum += *(p++);
    sum += *(p++);
    sum += *(p++);
    sum += *(p++);
}