The const keyword gives you the ability to define objects, function arguments, return values and member functions as constants, and to eliminate the preprocessor for value substitution without losing any preprocessor benefits. All this provides a significant additional form of type checking and safety in your programming. The use of so-called const correctness (the use of const anywhere you possibly can) can be a lifesaver for projects.

Although you can ignore const and continue to use old C coding practices, it’s there to help you. Chapters 11 and on begin using references heavily, and there you’ll see even more about how critical it is to use const with function arguments.