I have a long long formula, like
float a = sin(b)*cos(c)+sin(c+d)*sin(d)....
Is there a way to use
sin in C programming, to shorten the formula, without affecting the running time?
if I use define, does it affect runtime?
define works by doing text-based substitution at compile time. If you
#define s(x) sin(x) then the C pre-processor will rewrite all the
sin(x) before the compiler gets a chance to look at it.
BTW, this kind of low-level text-munging is exactly why define can be dangerous to use for more complex expressions. For example, one classic pitfall is that if you do something like
#define times(x, y) x*y then
times(1+1,2) rewrites to
1+1*2, which evaluates to
3 instead of the expected
4. For more complex expressions like it is often a good idea to use inlineable functions instead.