Homework 6
Due October 22, 2002
Solutions

6c) Three has 4 parameters and is of type char (character).
6d) Function test needs 4 actual parameters when called.  They are of type
int, character, double, and int, and should be ordered int,char,double,int.
6e) cout << test(5, 'z', 7.3, 5);

7a) 14
7b) 15
7c) 30

8ai) 125
8aii) 432
8b) The function secret cubes the value passed to it.

A.
Here is one solution:
bool is_leap_year(int year)
{
  if (year % 4 != 0)
    return false;
  if (year % 400 == 0)
    return true;
  if (year % 100 == 0)
    return false;
  return true;
}

B.
float min_of_three(float num1, float num2, float num3)
{
  float min = num1;

  if(num2 < min)
    min = num2;
  if(num3 < min)
    min = num3;

  return min;
}

C.
// assume we have done a #include <cctype>
bool is_vowel(char c)
{
  char lowercase = tolower(c);
  if(lowercase == 'a' || lowercase == 'e' || lowercase == 'i'
         || lowercase == 'o' || lowercase == 'u')
    return true;
  else return false;
}

D.
// assume we have already done a #include <cmath>
float distance(float x1, float y1, float x2, float y2)
{
  return sqrt((x2-x1)*(x2-x1)+(y2-y1)*(y2-y1));
}

E. The program prints out all numbers between 1 and the inputted number
   which are divisble by 6 

#include <iostream>
using namespace std;

bool divisible_by_six(int num);  // prototype for division function

int main()
{
  int pos;    // positive integer to be inputted by user
  int i;      // loop iterator

  // prompt user for input for variable pos
  cout << "Please type a positive integer: ";
  cin >> pos;

  if(!cin || pos < 0) {    // if no input or number is not positive
    cout << "Silly, user!  You did not follow directions!\n";
    return 1;              // end program with error condition
  }

  for (i = 1; i <= pos; i++) {  // repeat the following for integers 1 to pos
    if(divisible_by_six(i))     // if i is a multiple of 6,
      cout << i << " ";         // then output it 
  }

  return 0;        // end program without error condition
}

/* 
Purpose: This function takes a number and determines if it is divisible by 6
It does this by checking that it's divisible by both 2 and 3.
If the number is divisible (with no remainder) by both 2 and 3, then
we return true, otherwise we return false.  Note that this is an inefficient
way to do this!
*/
bool divisible_by_six(int num)
{
  if(num % 3 || num % 2)   // if num has a remainder of other than zero
                           // when we divide by either 2 or 3
    return false;          // then it's not divisible by 6
  else	
    return true;           // it's divisible by 6
}