inline function

[shardul316]

FOOD FOR THOUGHT:
by using inline function in c++ program we can increase th speed of
execution of prog/function.as keyword inline replaces the function call by
function code.
if this is true
then why don't we use keyword "inline" for all the functions to increase the speed of execution.?

[Banfa]

Because of the vast increase in code size that would result and the vastly increased amount of ram required(leading from the fact that since you have unraveled the program every variable that did exist on the stack and shared ram now has to have its own ram).

Additionally some functions just can be inlined (notably recursive ones).

In a large function the increase in code size and required memory almost certainly out weighs the increase in speed which is actually minimal for a single function call.

The speed saving in inlining is small and it therefore works best on functions that are call a lot and this tends to be small utility functions.


So in conclusion inlining it is generally best to not inline large functions that aren't called very often and to inline small functions that are called lots.