Lab 6 - Void functions

1. Write a program that computes the average and standard deviation of four integer scores. Your program will have three functions: get_input(), average() and std_dev(). To compute the standard deviation, you first compute (si - a)2 for each score, where a is the average and si is the value of the i-th score. You then take the sum of the results of this computation and divide by 4 (the sample size). Then take the square root of that result to get the standard deviation. See this Wikipedia article for the full equation for computing standard deviation and an example of estimating standard deviation from a sample.

   Your get_input() function will read the integers from a file, lab6.dat. You can copy this file to your current directory on Helios with the command:

   cp /usr/users/mdanfor/public_html/cs221-f06/lab6.dat . 

   For this particular problem, using the arrow operators (fin >> num1 for example) to read the entire file would be better suited. Refer to your notes from Wednes. lecture or Chapter 6 in the book.

   This is your main function. You will need to define the prototypes and bodies for get_input(), average() and std_dev().

   int main()
   {
     int num1, num2, num3, num4;
     double avg, std;
   
     get_input(num1, num2, num3, num4);
     avg = average(num1, num2, num3, num4);
     std = std_dev(num1, num2, num3, num4);
   
     printf("The average is %.2f and the standard deviation is %.2f.\n",
            avg, std);
   
     return 0;
   }
   

2. Copy lab6_1.cpp to lab6_2.cpp. At the end of your get_input() function add debugging output as follows:

   #ifdef DEBUG_ME
     printf("**DEBUG** read in from file: %d %d %d %d\n", num1, num2, num3, num4);
   #endif
   

   Also add a debugging statement to std_dev() that prints out the value of (si - a)2 for each score. Remember you will need to add #define DEBUG_ME at the top of your program (in the global scope) and recompile to see the debugging messages.