Beginning Mac OS® X Programming

A.3. Chapter 3

A.3.1. Exercise 1 solution

Use the proper man page requests that appear in the following table. Note that printf overlaps with a command-line function, so you must specifically request the section for C functions. The section is optional for the other man pages.

Function	Man Page
printf	"3 printf"
scanf	"scanf" or "3 scanf"
pow	"pow" or "3 pow"

A.3.2. Exercise 2 solution

1. Change the instances of int in Calculate.h to double. This includes

   double calculate(const double a, const double b, const char op);

2. Change the instances of int in Calculate.c to double. This includes:

   double calculate(const double a, const double b, const char op)
   {
       double result;

3. Replace the main function in main.c with the following code:

   int main (int argc, const char * argv[])
   {
       int count;
       double a, b, answer;
       char op;
   
       // print the prompt
       printf("Enter an expression: ");
   
       // get the expression
       count = scanf("%lg %c %lg", &a, &op, &b);
       if (count != 3) {
           printf("bad expression\n");
           exit(1);
       }
   
       // perform the computation
       answer = calculate(a, b, op);
   
       // print the answer
       printf("%lg %c %lg = %lg\n", a, op, b, answer);
   
       return 0;
   }

A.3.3. Exercise 3 solution

1. Add the following include after the other includes in Calculate.c:

   #include <math.h>

2. Add the following case entries to the switch statement. Here is the final switch statement:

   case '/':
               result = a / b;
               break;
           case '\\':
               result = (int)a / (int)b;
               break;
           case '%':
               result = (int)a % (int)b;
               break;
           case '^':
               result = pow(a, b);
               break;

   Your Calculate.c file ...