Preprocessor

1. Given the following definition

   #define DOUBLE(X) 2*X

   • What is the value of DOUBLE(1+2)
   • What is the value of 4/DOUBLE(2)
   • Fix the definition of DOUBLE, and test it.

2. Write a macro DISP(f,x) so that

   DISP(sqrt,3.0)

expands into

 printf("sqrt(%g) = %g\n", 3.0, sqrt(3.0));

Test your macro.

Structures and Unions

Given the following definitions

struct point { int x, y };
struct shape {
       enum { RECTANGLE, CIRCLE } shape_kind;
       struct point center;
       union {
         struct {
           int height, width;
         } rectangle;
         struct {
           int radius;
         } radius;
       } u;
}

Correct any of the following statements that are illegal:

1. s.shape_kind = RECTANGLE;

2. s.center.x = 10 ;

3. s.height = 25;

4. s.u.rectangle.width = 8;

5. s.u.circle=5;

6. s.u.radius=6;

Function pointers

Write the function sum with prototype

int sum(int (*f)(int), int start, int end)

The call sum(g,i,j) should return g(i)+g(i+1)+...+g(j)

• Chapter 16 Structures, Unions

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