Back to Main Page for Lecture 6
#include <iostream.h>
// function declaration
float cube_volume(float length, float height, float width);
// main body of program
main()
{
float length1,width1,height1,volume1;
float length2,width2,height2,volume2;
// input cube dimensions
cout << "Enter dimensions of cube 1\n";
cin >> length1 >> height1 >> width1;
cout << "Enter dimensions of cube 2\n";
cin >> length2 >> height2 >> width2;
// calculate volume
volume1 = cube_volume(length1,height1,width1);
volume2 = cube_volume(length2,height2,width2);
// output results
if (volume1 > volume2)
cout << "Cube 1 is largest, its volume is "
<< volume 1 << "\n";
else if (volume2 > volume1)
cout << "Cube 2 is largest, its volume is "
<< volume2 << "\n";
else
cout << "both cubes have equal volumes of "
<< volume1 << "\n";
}
// function definition
float cube_volume(float length, float height, float width)
{
float volume;
volume = length * width * height;
return(volume);
}
// Calculate train time table - using functions
#include <isotream.h>
//Function declarations
int to_24hr(int mins);
int to_mins(int hr_24);
main()
{
const int wait = 5;
int start, stop, time;
int start_min, stop_min;
int journey_time, freq_time;
int dep_red,dep_green,dep_yellow,arr_blue;
int dep_red_min,dep_green_min,dep_yellow_min,arr_blue_min;
cout << "Enter the journey time (minutes)\n";
cin >> journey_time;
cout << "Enter the first train time\n";
cin >> start;
cout << "Enter the last train time\n";
cin >> stop;
cout << "Enter the frequency time\n";
cin >> freq_time;
// convert start and stop times to minutes
start_min = to_mins(start);
stop_min = to_mins(stop);
// table header
cout << "RED \t GREEN \t YELLOW \t BLUE\n";
for (time=start_min; time<=stop_min; time+=freq_time)
{
// Calculate Times
dep_red_min = time;
dep_green_min = (time + journey_time + wait);
dep_yellow_min = (time + 2*(journey_time + wait));
arr_blue_min = time + 3*journey_time +2*wait;
// Convert times to 24 hour clock to display
dep_red = to_24hr(dep_red_min);
dep_green = to_24hr(dep_green_min);
dep_yellow = to_24hr(dep_yellow_min );
arr_blue = to_24hr(arr_blue_min);
cout << dep_red << "\t" << dep_green << "\t"
<< dep_yellow << "\t" << arr_blue << "\n";
}
} // end of main program
// Definition of to_24hr function
int to_24hr(int mins)
{
int hr, min, total;
hr = mins/60;
min = mins%60;
total = hr*100 + min;
return (total);
}
// Definition of to_mins function
int to_mins(int hr_24)
{
int hr, min, total_mins;
hr = hr_24/100;
min = hr_24%100;
total_mins = hr*60 + min;
return(total_mins);
}
// Program to calculate the factorials of positive integers
// Program prints results for integers from 0 to 10
#include <iostream.h>
long factorial (int n);
main()
{
int j;
for (j=0;j < 11;j++)
cout << j << "! = " << factorial(j) << "\n";
}
long factorial (int n)
{
long result;
if (n==0)
result = 1;
else
result = n * factorial(n-1);
return(result);
}
#include <math.h>
#include <iostream.h>
struct coord {
float x,y,z;
};
// function declarations
float length (coord point1, coord point2);
float square (float x);
void main (void)
{
coord p1, p2;
float line_length;
cout << "Enter coords of point 1 : ";
cin >> p1.x >> p1.y >> p1.z;
cout << "Enter coords of point 2 : ";
cin >> p2.x >> p2.y >> p2.z;
line_length = length(p1, p2);
cout << "Length = " << line_length << "\n";
}
float length (coord point1, coord point2)
{
float xlen,ylen,zlen;
float len_sqr;
xlen = point1.x - point2.x;
ylen = point1.y - point2.y;
zlen = point1.z - point2.z;
len_sqr = square(xlen) + square(ylen) + square(zlen) ;
return (sqrt(len_sqr));
}
float square (float x)
{
return ((x)*(x));
}
This example illustrates how reference variables can be used to permit a function to change values in the calling program.
#include <iostream.h>
void swap(int &ra, int &rb);
main()
{
int a,b;
a = 10;
b = 12;
swap (a,b);
}
void swap(int &ra, int &rb)
{
int temp;
temp = ra;
ra = rb;
rb = temp;
}
This example sends an array to the function. The function then calculates both the largest and smallest value stored in the array. These maximum and minimum values stored are then returned to the main calling program as function arguments.
There is a msitake in the notes, the following program is correct and has made MAX be global so the function also knows its value. An alternative solution is given below where MAX is local and is sent to the function.
#include <iostream.h>
#include <math.h>
void max_min(float &max, float &min, float array[]);
const int MAX = 5;
main()
{
float array1[MAX];
float array2[MAX];
float max1, min1;
float max2, min2;
int i;
for (i=0; i<MAX;i++)
{
cout << "Enter value "<< i << " of array1\n";
cin >> array1[i];
}
for (i=0; i<MAX;i++)
{
cout << "Enter value "<< i << " of array2\n";
cin >> array2[i];
}
max_min(max1,min1,array1);
max_min(max2,min2,array2);
cout << "Array 1 : max = " << max1 << " min = " << min1 << "\n";
cout << "Array 2 : max = " << max2 << " min = " << min2 << "\n";
}
void max_min(float &max, float &min, float array[])
{
int i;
min = array[0];
max = array[0];
for (i=1;i < MAX;i++)
{
if (array[i] > max)
max = array[i];
if (array[i] < min)
min = array[i];
}
}
#include <iostream.h>
#include <math.h>
void max_min(int size_array, float &max, float &min, float array[]);
main()
{
const int MAX = 5;
float array1[MAX];
float array2[MAX];
float max1, min1;
float max2, min2;
int i;
for (i=0; i<MAX;i++)
{
cout << "Enter value "<< i << " of array1\n";
cin >> array1[i];
}
for (i=0; i<MAX;i++)
{
cout << "Enter value "<< i << " of array2\n";
cin >> array2[i];
}
max_min(MAX, max1,min1,array1);
max_min(MAX, max2,min2,array2);
cout << "Array 1 : max = " << max1 << " min = " << min1 << "\n";
cout << "Array 2 : max = " << max2 << " min = " << min2 << "\n";
}
void max_min(int size_array, float &max, float &min, float array[])
{
int i;
min = array[0];
max = array[0];
for (i=1;i < size_array;i++)
{
if (array[i] > max)
max = array[i];
if (array[i] < min)
min = array[i];
}
}
A sports timer can time an event returning the elapsed time in seconds. Write a function to convert the time in seconds to hours, minutes and seconds, returning these values as function arguments. The function should be called from a main calling program where the user is prompted to enter the elapsed time in seconds.
Reference variable must be used in the function arguments for hours, minutes and seconds.
#include <iostream.h>
#include <math.h>
// Function Declaration
void change_time(int elapsed_seconds, int &hours, int &mins, int &seconds);
main()
{
int elapsed_time;
int time_hours, time_minutes, time_seconds;
cout << "Enter the time for the event\n";
cin >> elapsed_time;
//Function call - send address of variables to change
change_time(elapsed_time, time_hours, time_minutes, time_seconds);
// Use variables as normal
cout << "The number of hours is " << time_hours << " \n";
cout << "The number of minutes is "<< time_minutes << " \n";
cout << "The number of seconds is " << time_seconds << " \n";
cout << "The number of seconds is " << time_seconds << " \n";
}
// Function to convert total in seconds to hours, mins and seconds
void change_time(int elapsed_seconds, int &hours, int &mins, int &seconds)
{
int tmp_minutes;
seconds = elapsed_seconds%60;
tmp_minutes = elapsed_seconds/60;
mins = tmp_minutes%60;
hours = tmp_minutes /60;
}
| Back to Main Page for Lecture 6 |