UMBC CMSC 104 - Fall 2017 - Solutions for Class 7 & 8 assignments

functions.c

#include <stdio.h>

double areaOfCircle(double radius)
{
  return radius * radius * 3.14;
}

double areaOfSquare(double lengthOfSide)
{
  return lengthOfSide * lengthOfSide;
}

double areaOfTriangle(double base, double height)
{
  return base * height * 0.5;
}

void printSum(int x, int y)
{
  printf("The sum is %d\n", x + y);
}

void printArea(double radius)
{
  printf("The area is %lf\n", areaOfCircle(radius));
}

double totalCost(double costOfItem, int quantity)
{
  // This is an example of where it's ok to use
  // an int and a double in the same math operation
  // the result of an int multipled by a double
  // is a double, so we don't lose any precision.
  // Also, logically - quantity makes more sense
  // as an int.
  return costOfItem * quantity;
}

double salesTax(double price)
{
  return price * 1.06;
}

void printTotalCostWithTax(double costOfItem, int quantity)
{
  double costWithoutTax = totalCost(costOfItem, quantity);
  printf("total cost with tax is %lf\n", salesTax(costWithoutTax));
}

int main()
{
  /* part 7.1 */
  double areaOfCircleWithRadius10 = areaOfCircle(10);
  printf("The area of a circle is %lf\n", areaOfCircleWithRadius10);
  // Other than the value used for radius, line 58 results in the same
  // thing as lines 53-54. Either method is correct for each part of
  // this assignment.
  printf("The area of a circle is %lf\n", areaOfCircle(20));

  /* part 7.2 */
  printf("The area of a square is %lf\n", areaOfSquare(10));
  printf("The area of a square is %lf\n", areaOfSquare(20));

  /* part 7.3 */
  printf("The area of a triangle is %lf\n", areaOfTriangle(10, 5));
  printf("The area of a triangle is %lf\n", areaOfTriangle(20, 5));

  /* part 7.4 */
  printSum(4, 6);

  /* part 8.1 */
  printArea(10);

  /* part 8.2 */
  printf("The total cost is: %lf\n", totalCost(12.0, 10));

  /* part 8.3 */
  printf("Total with tax applied to $120 is: %lf\n", salesTax(120.0));

  /* part 8.4 */
  printTotalCostWithTax(12.0, 10);

  return 0;
}