KSU CS3540 Assignment 3

Modify the "grades" program so that the user initially enters the number of grades and then enters the grades.  The program will output the average of the grades, the standard deviation of the grades, and the median of the grades.  Please email your source code to your instructor by 9:30 am on  Tuesday, January 21^st. 

/* Name : Dalibor Labudovic
   Course: CS3540 Sec. 2
   Prof. : J. Higgins
*/

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

//function prototype

int* get_data(int num_grades); // function to get grades

//function to calculate average and display results
float calc_average(int num_grades, int* grades);
void display_average(float average);

//function to clculate median and display results
float calc_median(int num_grades, int* grades);
void display_median(float median);

//function to calculate standard deviation and display results
float calc_standard_deviation(int num_grades, int* grades);
void display_stdDev(float stdDev);


const int MAX_GRADE = 100;

int main(){
    int* grades;
    int num_grades;
    printf("Enter the number of grades: ");
    scanf("%d", &num_grades);
   
    //invoke get data function passing num_grades
        grades = get_data(num_grades);
   
   
        float average = calc_average(num_grades, grades);
        display_average(average);

        float median = calc_median(num_grades, grades);
        display_median(median);

        float stdDev = calc_standard_deviation(num_grades, grades);
        display_stdDev(stdDev);

        free(grades);
      return 0;
}

//function to get input data
//prepost conditions
//num_grades != NULL
//
//postconditions
//grades != NULL
int* get_data(int num_grades)
{    assert(num_grades != NULL);
    assert(num_grades > 0);
    int* grades = malloc(num_grades * sizeof(int));
    int i;
        for (i = 0; i < num_grades; i++){
                printf("enter grade: ");
        int grade;
                scanf("%d", &grade);
                while(grade < 0 && grade > MAX_GRADE)
                {
                        printf("Grades need to be >= 0 and <= 100: Try Again!\n");
                        printf("enter a grade: ");
                        scanf("%d", &grade);
                }
                grades[i] = grade;
        }
    assert(grades != NULL);
    return grades;
}
//function to calcuate the median grade
float calc_median(int num_grades, int* grades)
{
    //sort
    float temp;
        int i,j;
            for(i = 1;i <= num_grades; i++)

            for(j = 1; j <= num_grades - 1; j++)
            {
                if(grades[i] > grades[j])
                    {
                        temp = grades[j];
                        grades[j] = grades[j+1];
                        grades[j+1] = temp;
                    }
            }

            if( num_grades % 2 == 0)
                return (grades[num_grades/2] + grades[num_grades/2+1])/2;
            else
                return grades[num_grades/2 + 1];
}
void display_median(float median)
{
    printf("Median %.2f\n", median);
}
//function to calcuate the average grade
float calc_average(int num_grades, int* grades)
{
    int sum = 0;
    float average;
    if(num_grades == 0) printf("No grades to average\n");
    else{
        int i;
        for(i=0; i < num_grades; i++){
            sum +=grades[i];
        }
        average = (float) sum/num_grades;
    }
    return average;
}
void display_average(float average)
{
    printf("Average: %.2f\n", average);
}
//function to calculate the standard deviation
float calc_standard_deviation(int num_grades, int* grades)
{
//find the mean
    float mean = 0.0;
    float sum_deviation = 0.0;
    int i;
    for(i = 0; i < num_grades; i++)
    {
        mean += grades[i];
    }
    mean = mean/num_grades;

    for(i = 0; i < num_grades; i++)
    sum_deviation += (grades[i] - mean)* (grades[i] - mean);
    float stdDev = sqrt(sum_deviation/num_grades);
    return stdDev;
}
void display_stdDev(float stdDev)
{
    printf("Standard Deviation %.2f\n", stdDev);

}