6.2 const usage

1. Const usage:

1) define a const constant

2) const can modify the parameters and return values of a function, or even the definition body of a function. All things modified by const are protected by force, which can prevent unexpected changes and improve program robustness.

2. What is the difference between const and # define?

The C ++ language can use const to define constants or # define to define constants, but the former has more advantages than the latter.

1) const constants have data types, while macro constants do not. The compiler can perform type security checks on the former, while only character replacement on the latter, without type security checks, and unexpected errors (marginal effect) may occur during character replacement ).

2) some integrated debugging tools can debug const constants, but cannot debug macro constants. In the C ++ program, only the const constant is used instead of the macro constant, that is, the const constant completely replaces the macro constant.

In this way, it seems that the method of writing a program is very informal. In the future, pay attention to using the const type for processing.