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PRE00-EX1: Macros can be used to implement local functions (repetitive blocks of code that have access to automatic variables from the enclosing scope) that cannot be achieved with inline functions.

PRE00-EX2: Macros can also be made to support certain forms of lazy calculation that cannot be achieved with an inline functionbe used for concatenating tokens or performing stringification. For example,

#define SELECT(s, v1, v2) ((s) ? (v1) : (v2))enum Color { Color_Red, Color_Green, Color_Blue };
static const struct {
  enum Color  color;
  const char *name;
} colors[] = {
#define COLOR(color)   { Color_ ## color, #color }
  COLOR(Red), COLOR(Green), COLOR(Blue)
};

See [PRE05-C. Understand macro replacement when concatenating tokens or performing stringification] for more information.

calculates only one of the two expressions depending on the selector's value.

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