A function can be declared with either pointer arguments or array
arguments. The C standard considers these to be equivalent. However, it
is useful to distinguish between the case of a pointer, representing a
single object which is being modified, and an array which represents a
set of objects with unit stride (that are modified or not depending on
the presence of const). For vectors, where the stride is not
required to be unity, the pointer form is preferred.
/* real value, set on output */ int foo (double * x); /* real vector, modified */ int foo (double * x, size_t stride, size_t n); /* constant real vector */ int foo (const double * x, size_t stride, size_t n); /* real array, modified */ int bar (double x[], size_t n); /* real array, not modified */ int baz (const double x[], size_t n);