In C++, there is one good feature called inline function. This kind of functions are like the macros of C or C++. To use inline functions, we have to specify the inline keyword. We can use this type of functions anywhere, but we should follow some guideline.
When inline can be used?
Inline functions can be used in the place of macros (#define)
For small functions we can use inline functions. It creates faster code and smaller executables.
When functions are small and called very often, we can use inline.
When we should avoid the use of inline?
We should not use functions that are I/O bound as inline functions.
When large code is used in some function, then we should avoid the inline.
When recursion is used, inline function may not work properly.
One point we have to keep in mind, that inline is not a command. It is a request. So we are requesting the compiler to use inline functions. If the compiler decides that the current function should not be an inline function, it can convert it into normal function.