Therefore, you may have noticed that not all the lines of this program did an action. The program has been structured in different lines in order to be more readable, but it is not compulsory to do so. The division of code in different lines serves only to make it more legible and schematic for the humans that may read it. And the result would have been exactly the same than in the previous examples. They are lines read and discarded by the preprocessor that finaly do not produce any code.
Comments are pieces of source code discarded from the code by the compiler.
They do nothing. Their purpose is only to allow the programmer to insert notes or descriptions embedded within the source code. Standard Header Files .