Topical Information

Here are a few questions to help you clarify your understanding of re-using functions.

Question Set Information

Questions

1. Given the following function, name three (3) places you might use it in an application:

       // Clears the Screen
       //
       // Input:  none
       // Output:  none
       //
       // Action:  makes the entire screen blank...
       void clear_screen(void);
   

   
           
   
           
   just as we begin main
           
   before user input
           
   before results are displayed
           
   ...
           
   
   

2. Given the following function description, state three (3) different applications you might find for it (three situations where you might use it):

       // Validate Ranged Input
       //
       // Input:  prompt string, lower bound, upper bound
       // Output:  valid value entered from user
       //
       // Action:  prints caller's prompt, reads user's entry,
       //          if their entry isn't in the specified range
       //          (inclusive), prints an error message and
       //          forces re-entry, otherwise returns valid
       //          entry
       //
       // Sample call:
       //
       //     user_ent = range_input("This is your prompt:  ", -4, 4);
   

   
           
   
           
   reading a score for a test having a known maximum number of points
           
   reading a die-roll total for a known set of dice
           
   reading the Arabic numeral for a Roman numeral conversion program
           
   reading the number of categories for a basket of flowers at the Busy Bee
               Blossom Boutique
           
   ...
           
   
   

3. Given the following function description, find three (3) applications for it (three situations where you might use such a function):

       // Find Char in String
       //
       // Input:  string to search, character to find
       // Output:  position of character in string (-1 if not found)
       //
       // Action:  searches through the string for the specified
       //          character; if not found, returns -1; if found
       //          indicates its position as an offset from the
       //          start of the string (the first position is 0 away
       //          from the start of the string)
       //
       // Sample call:
       //
       //     offset = find("this is your string", ' ');
   

   
           
   
           
   determine the presence of a period in a string
           
   find the first occurrence of a hyphen in a string
           
   use in a loop and in conjunction with a replacement function to translate a string
               into 13&+ speak
           
   ...
           
   
   

4. Given the following function, explain how you might use it in the given situations. (Actual code is preferred.)

       // Sum Numbers
       //
       // Input:  two numbers
       // Output:  sum of the numbers
       //
       // Action:  adds its two numeric arguments and returns the sum
       double sum(double x, double y);
   

   1. add 3 numbers

      
              sum( sum( a, b ), c )
      
      

   2. average 2 numbers

      
              sum( a, b ) / 2
      
      

   3. subtract 2 numbers

      
              sum( a, -b )
      
      

5. Given the following function, explain how you might use it in the given situations. (Actual code is preferred.)

       // Average Numbers
       //
       // Input:  two numbers
       // Output:  average of the numbers
       //
       // Action:  adds its two numeric arguments and returns the sum
       //          divided by 2
       double avg(double x, double y);
   

   1. find a midpoint
      (Hint: 2D, right?)

      
              mid_x = avg( x1, x2 );
              mid_y = avg( y1, y2 );
      
      

   2. calculate the expected value of a dice roll
      (Hint: Statistics are so weird!)

      
              expect = avg( min_roll, max_roll );
      
      

   3. sum 2 numbers

      
              avg( a, b ) * 2