Programming in C

320 Chapter 13 The Preprocessor

Exercises

1. Type in and run the three programs presented in this chapter, remembering to
   type in the include file associated with Program 13.3. Compare the output pro-
   duced by each program with the output presented in the text.


2. Locate the system header files <stdio.h>,<limits.h>,and <float.h>on your
   system (on Unix systems, look inside the /usr/includedirectory). Examine the
   files to see what’s in them.


3. Define a macro MINthat gives the minimum of two values.Then write a program
   to test the macro definition.


4. Define a macro MAX3that gives the maximum of three values.Write a program to
   test the definition.


5. Write a macro SHIFTto perform the identical purpose as the shiftfunction of
   Program 12.3.


6. Write a macro IS_UPPER_CASEthat gives a nonzero value if a character is an
   uppercase letter.


7. Write a macro IS_ALPHABETICthat gives a nonzero value if a character is an
   alphabetic character. Have the macro use the IS_LOWER_CASEmacro defined in the
   chapter text and the IS_UPPER_CASEmacro defined in exercise 6.


8. Write a macro IS_DIGITthat gives a nonzero value if a character is a digit '0'
   through '9'.Use this macro in the definition of another macro IS_SPECIAL,
   which gives a nonzero result if a character is a special character; that is, not alpha-
   betic and not a digit. Be certain to use the IS_ALPHABETICmacro developed in
   exercise 7.


9. Write a macro ABSOLUTE_VALUEthat computes the absolute value of its argument.
   Make certain that an expression such as
   ABSOLUTE_VALUE (x + delta)

is properly evaluated by the macro.

10. Consider the definition of the printintmacro from this chapter:
    #define printint(n) printf ("%i\n", x ## n)

Could the following be used to display the values of the 100 variables x1–x100?

Why or why not?

for (i = 1; i < 100; ++i)

printx (i);

11. Test out the system library functions that are equivalent to the macros you devel-
    oped in exercises 6, 7, and 8.The library functions are called isupper,isalpha,
    and isdigit.You need to include the systemheader file <ctype.h>in your pro-
    gram in order to use them.