/****
 *
 * This program computes simple statistics for numbers read from standard
 * input.  The program first asks for the number of values that the statistics
 * will be computed for.  The program then reads in that many values.
 *
 * The statistics computed are the sum of the numbers and the arithmetic mean.
 * The results are printed to standard output, in the following form:
 *
 * Sum = 
 * Mean =
 *
 * The precise formula for the mean is defined here:
 *
 *    http://www.gcseguide.co.uk/statistics_and_probability.htm
 *
 *
 * Author: Gene Fisher (gfisher@calpoly.edu)
 * Created: 14apr11
 * Last Modified: 14apr11
 *
 */

#include <stdio.h>
#include <math.h>

int main () {

    int n;                      /* Number of values to compute stats for */
    double x;                   /* Input value read from the terminal */
    double sum;                 /* Computed sum */
    int i;                      /* Loop counter variable */

    /*
     * Input the number of values, and prompt for the rest of the data values.
     */
    printf("Input the number of values you want to compute stats for: ");
    scanf("%d", &n);
    printf("Input the values, separated by whitespace: ");

    /*
     * Initialize the sum to 0.
     */
    sum = 0;

    /* 
     * Compared to the while loop version of the program, the statement to
     * initialize the loop counter is missing here.  This is because the
     * initialization happens in for loop initialization expression, i.e., the
     * first part of the for loop heading.
     */

    /*
     * Loop until all the values are read in, accumulating the sum as we go.
     * Note that the loop will not go at all if the user enters a non-positive
     * value for the number of data points.
     */
    for (i = 0; i < n; i++) {

        /*
         * Input the next value.
         */
        scanf("%lf", &x);

        /*
         * Increment the sum.
         */
        sum = sum + x;

        /* 
         * Compared to the while loop version of the program, the statement to
         * increment the loop counter is missing here.  This is because the
         * incrementing happens in for loop update expression, i.e., the third
         * part of the for loop heading.
         */

    }

    /*
     * Output the results.
     */
     printf("Sum = %f\n", sum);
     printf("Mean = %f\n", sum / n);

    return 0;

}