Is a += b more efficient than a = a + b in C?

Question

I know in some languages the following:

a += b

is more efficient than:

a = a + b

because it removes the n

Answer 1

Other than with a truly ancient or incompetently written compiler there should be no difference, as long as a and b are normal variables so the two produce equivalent results.

If you were dealing with C++ rather than C, operator overloading would allow there to be more substantial differences though.