Question

Is this C code:

/* LERP(a,b,c) = linear interpolation macro, is 'a' when c == 0.0 and 'b' when c == 1.0 */
#define LERP(a,b,c)     (((b) - (a)) * (c) + (a))

http://www.brucelindbloom.com/index.html?Eqn_XYZ_to_T.html

Equals this C# code?

private static double LERP(double a, double b, double c) { return (((b) - (a)) * (c) + (a)); }

?

Answer 1

no.
consider the following:

LERP(x++,1,2);

The c code might also have a side effect of increasing x twice [it is undefined as mentioned by @phresnel], while the c# code is perfectly defined, and will increase x only once.

the result also might be different, since the first a and the second one [in the macro] might have a different value, since it might have increased in the first one.