Benefits of declaring a function as “inline”?

Question

Every time I read about the \"inline\" declaration in C it is mentioned that it is only a hint to the compiler (i.e. it does not have to obey it). Is there any benefit to ad

Answer 1

It provides a simple mechanism for the compiler to apply more OPTIMIZATIONS.
Inline functions are faster because you don't need to push and pop things on/off the stack like parameters and the return address; however, it does make your binary slightly larger.

Does it make a significant difference? Not noticeably enough on modern hardware for most. But it can make a difference, which is enough for some people.

Marking something inline does not give you a guarantee that it will be inline. It's just a suggestion to the compiler. Sometimes it's not possible such as when you have a virtual function, or when there is recursion involved. And sometimes the compiler just chooses not to use it. I could see a situation like this making a detectable difference:

inline int aplusb_pow2(int a, int b) {
  return (a + b)*(a + b) ;
}

for(int a = 0; a < 900000; ++a)
    for(int b = 0; b < 900000; ++b)
        aplusb_pow2(a, b);