Programming in C

162 Chapter 8 Working with Functions

Exercises

1. Type in and run the 16 programs presented in this chapter. Compare the output
   produced by each program with the output presented after each program in the
   text.


2. Modify Program 8.4 so the value of triangularNumberis returned by the func-
   tion.Then go back to Program 5.5 and change that program so that it calls the
   new version of the calculateTriangularNumberfunction.


3. Modify Program 8.8 so that the value of epsilonis passed as an argument to the
   function.Try experimenting with different values of epsilonto see the effect that
   it has on the value of the square root.


4. Modify Program 8.8 so that the value of guessis printed each time through the
   whileloop. Notice how quickly the value of guessconverges to the square root.
   What conclusions can you reach about the number of iterations through the loop,
   the number whose square root is being calculated, and the value of the initial
   guess?


5. The criteria used for termination of the loop in the squareRootfunction of
   Program 8.8 is not suitable for use when computing the square root of very large
   or very small numbers. Rather than comparing the differencebetween the value of
   xand the value of guess^2 , the program should compare the ratioof the two values
   to 1.The closer this ratio gets to 1, the more accurate the approximation of the
   square root.
   Modify Program 8.8 so this new termination criteria is used.


6. Modify Program 8.8 so that the squareRootfunction accepts a double precision
   argument and returns the result as a double precision value. Be certain to change
   the value of the variable epsilonto reflect the fact that double precision variables
   are now being used.


7. Write a function that raises an integer to a positive integer power. Call the func-
   tion x_to_the_ntaking two integer arguments xand n.Have the function return
   a long int,which represents the results of calculating xn.


8. An equation of the form
   ax^2 + bx + c = 0

is known as a quadraticequation.The values of a,b,and cin the preceding example

represent constant values. So

4x^2 - 17x - 15 = 0