Effective C++读书笔记(3)-Item 2: Prefer consts, enums, and inlines to #defines

                         Item 2: Prefer consts, enums, and inlines to #defines  

This Item might better be called "prefer the compiler to the preprocessor“

#define ASPECT_RATIO 1.653

The solution is to replace the macro with a constant:

const double Aspecratio=1.653s

When replacing #defines with constants, two special cases are worth mentioning:

1.defining constant pointers.

const char* const authorName="Scott Meyers";

2.class-specific constants.To limit the scope of a constant to a class, you must make it a member, and to ensure there's at most one copy of the constant, you must make it a static member:

class GamePlayer

{

private:

static const int NumTurns=5; // constant declaration

        int scores[NumTurns]; // use of constant

        ....

}

Things to Remember

• For simple constants, prefer const objects or enums to #defines.

• For function-like macros, prefer inline functions to #defines.