There\'s two things about inlining:
inline
keyword will be ignored if the compiler determines that the function cannot be inlined.You may not want to inline everywhere it is possible. This could increase the size of your binaries too much. You may have a select few functions that aren't used very much that inlining would allow to run faster without increasing the size of your bits significantly
Manual use of inline
might be useful on older compilers or less sophisticated compilers (such as compilers for embedded development). If you're using visual studio, I don't think you typically need to use the inline
keyword at all.