Solution:
main.cpp:
#include <iostream>
#include "hmean.h"
int main ()
{
float x, y;
do {
std::cout << "Enter two numbers: ";
std::cin >> x >> y;
if (((x != 0) && (y != 0)))
std::cout << "Harmonic mean = " << harmonic_mean(x, y) << "\n";
} while ((x != 0) && (y != 0));
return 0;
}
hmean.h:
#pragma once
float harmonic_mean (float x, float y);
hmean.cpp:
#include "hmean.h"
float harmonic_mean (float x, float y)
{
return ((2 * x * y) / (x + y));
}
Solution:
main.cpp:
#include <iostream>
#include <vector>
#include <string>
#include <stdexcept>
#include "fn.h"
int main (int argc, char* argv)
{
std::vector<std::string> args (argv, argv+argc);
if (args.size() < 2)
throw std::runtime_error ("expected floating-point value as argument");
float x = std::stod (args[1]);
float val = f(x);
std::cout << "Value of expression = " << val << "\n";
return 0;
}
fn.h:
#pragma once
float f (float x);
fn.cpp:
#include "fn.h"
float f (float x)
{
float result;
result = x * x * x;
result -= 5.0 * x * x;
result += 12.0 * x;
result -= 24.0;
return result;
}
Solution:
main.cpp:
#include <iostream>
#include <vector>
#include <string>
#include <stdexcept>
#include "convert.h"
int main (int argc, char* argv)
{
std::vector<std::string> args (argv, argv+argc);
if (args.size() < 2)
throw std::runtime_error ("expected value in HU as argument");
std::cout << hu << " HU = " << HU_to_AC(hu) << " cm -1\n";
return 0;
}
convert.h:
#pragma once
float HU_to_AC (float hu);
convert.cpp:
#include <iostream>
#include "convert.h"
float HU_to_AC (float hu)
{
if (hu <= 0.0)
return 0.093 + hu * 0.000093;
else
return 0.093 + hu * 0.000055031;
}
Solution:
main.cpp:
#include <iostream>
#include <vector>
#include <string>
#include "prime.h"
int main (int argc, char* argv)
{
std::vector<std::string> args (argv, argv+argc);
int num = 50;
if (args.size() > 1)
num = std::stoi (args[1]);
display_primes (num);
return 0;
}
prime.h:
#pragma once
bool is_prime (int i);
void display_primes (int n = 50);
prime.cpp:
#include <iostream>
#include "prime.h"
bool is_prime (int i)
{
// special case: 1 is not prime
if (i == 1)
return false;
for (int j = 2; j < i; j++)
if ((i % j) == 0)
return false;
return true;
}
void display_primes (int n)
{
std::cout << "prime numbers up to " << n << ": ";
for (int i = 1; i <= n; i++) {
if (is_prime(i))
std::cout << i << " ";
}
std::cout << "\n";
}
Solution:
main.cpp:
#include <iostream>
#include <string>
#include <vector>
#include <stdexcept>
#include "rlencode.h"
// program to perform run -length encoding on string
int main (int argc, char* argv)
{
std::vector<std::string> args (argv, argv+argc);
if (args.size() < 2)
throw std::runtime_error ("expected string as argument");
rl_encode (args[1]);
return 0;
}
rlencode.h:
#pragma once
#include <string>
void rl_encode (const std:: string& str);
rlencode.cpp:
#include <iostream>
#include <string>
#include "rlencode.h"
void rl_encode (const std::string& str)
{
char c = str [0];
int count = 1;
for (auto n : str) {
if (n == c)
count++;
else {
std::cout << static_cast<int>(c) << " " << count << " ";
c = n;
count = 1;
}
}
std::cout << static_cast<int>(c) << " " << count << "\n";
}
The two errors were:
sphere.h) and function signature (in sphere.cpp) of the
sphere() function do not match. The argument to the function in sphere.cpp
should be float, not int.main() function. Its definition should be moved to the sphere.cpp file. Or,
alternatively, the built-in M_PI constant from the <cmath> include file can
be used.Corrected code:
main.cpp:
#include <iostream >
#include "sphere.h"
int main () {
float r;
do {
std::cout << "Enter radius (type -ve number to stop ) ";
std::cin >> r;
if (r >= 0.0)
std::cout << "V = " << sphere(r) << "\n";
} while (r >= 0.0);
}
sphere.h:
#pragma once
float sphere (float);
sphere.cpp:
#include "sphere.h"
float sphere (float r)
{
const float pi = 3.14159265;
float cube = r * r * r;
return ((4.0 * pi * cube) / 3.0);
}
main.cpp:
#include <iostream>
#include "sphere.h"
int main () {
float r;
do {
cout << "Enter radius (type -ve number to stop): ";
cin >> r;
if (r < 0)
break;
auto m = sphere (r);
std::cout << "V = " << m.vol << ", A = " << m.area << endl;
} while (r >= 0);
}
sphere.h:
#pragma once
struct VolArea {
float vol, area;
};
VolArea sphere (float r);
sphere.cpp:
#include "sphere.h"
VolArea sphere (float r)
{
const float pi = 3.14159265;
float cube = r * r * r;
return { (4.0 * pi * cube) / 3.0, 4.0 * pi * r * r };
}
Solution:
main.cpp:
#include <iostream >
#include "reverse.h"
// program to print out in reverse order
// characters read from keyboard
int main ()
{
reverse ();
return 0;
}
reverse.h:
#pragma once
void reverse ();
reverse.cpp:
#include <iostream>
#include "reverse.h"
void reverse ()
{
char ch;
std::cin.get(ch);
if (ch != '\n') {
reverse ();
std::cout.put(ch);
}
}
main.cpp:
#include <iostream>
#include "conv_bin.h"
// program to convert decimal to binary
int main ()
{
int n;
std::cout << "Enter decimal number (0 -255): ";
std::cin >> n;
conv_bin(n ,1);
return 0;
}
conv_bin.h:
#pragma once
void conv_bin(int n, int unit);
conv_bin.cpp:
#include <iostream>
#include "conv_bin.h"
void conv_bin (int n, int unit)
{
if (unit > 128)
return;
conv_bin (n/2, unit*2);
std::cout << n%2;
}
main.cpp:
#include <iostream>
#include "conv_bin.h"
// program to convert decimal to binary
int main ()
{
int n;
std::cout << "Enter decimal number (0 -255): ";
std::cin >> n;
conv_bin(n);
return 0;
}
conv_bin.h:
#pragma once
void conv_bin (int);
conv_bin.cpp:
#include <iostream>
#include "conv_bin.h"
void conv_bin (int n)
{
int res = n;
for (int i = 128; i > 0; i /= 2) {
std::cout << res / i;
res = res % i;
}
}
Solution:
main.cpp:
#include <iostream>
#include "hanoi.h"
int main ()
{
// move 3 disks from peg 1 to peg 3 using peg 2 as spare:
tower (3, 1, 3, 2);
return 0;
}
hanoi.h:
#pragma once
void tower (int n, int from, int to, int spare);
hanoi.cpp:
#include <iostream >
#include "hanoi.h"
void tower (int n, int from, int to, int spare)
{
if (n == 1) // anchor condition
std::cout << "move disk from peg " << from << " to peg " << to << endl;
else { // inductive step
tower (n - 1, from , spare , to);
std::cout << "move disk from peg " << from << " to peg " << to << endl;
tower (n - 1, spare , to , from );
}
}
Solution:
main.cpp:
#include <iostream>
#include <string>
#include <vector>
#include <stdexcept>
#include "trig.h"
// program to compute trigonometric functions using indirect recursion
int main (int argc, char* argv)
{
std::vector<std::string> args (argv, argv+argc);
if (args.size() < 3)
throw std::runtime_error ("expected function and value as arguments");
float x = std::stod (args[2]);
float result;
if (args[1] == "sin")
result = mysin(x);
else if (args[1] == "cos")
result = mycos(x);
else if (args[1] == "tan")
result = mytan(x);
else
throw std::runtime_error ("invalid function name: \"" + args[1] + "\"");
std::cout << "Result: " << args[1] << "(" << x << ") = " << result << "\n";
}
trig.h:
#pragma once
float mysin (float x);
float mytan (float x);
float mycos (float x);
trig.cpp:
#include "trig.h"
const float small = 0.1;
float mysin (float x)
{
if (x < small)
return x - x * x * x / 6.0;
float sin_term = mysin(x / 3.0);
float tan_squared = mytan(x / 3.0);
tan_squared *= tan_squared;
float tan_denom = 3.0 - tan_squared;
float tan_numer = 1.0 + tan_squared;
return sin_term * tan_denom / tan_numer;
}
float mytan (float x) {
return mysin(x) / mycos(x);
}
float mycos (float x) {
return 1 - mysin(x / 2);
}
Solution:
main.cpp:
#include <iostream>
#include <cmath>
#include <stdexcept>
double model (double a, double b, double c)
{
if (c <= -1.0)
throw std::runtime_error ("c must be larger than -1");
if (c == 0.0)
throw std::runtime_error ("c must be non -zero");
double x = a - b / std::log (c + 1.0);
if (x < 0.0)
throw std::runtime_error ("a must be larger than b/log(c+1)");
return std::sqrt (x);
}
int main ()
{
std::vector<std::string> args (argv, argv+argc);
if (args.size() < 4)
throw std::runtime_error ("expected 3 floating-point arguments");
try {
double a = std::stod (args[1]);
double b = std::stod (args[2]);
double c = std::stod (args[3]);
double value = model (a, b, c);
std::cout << "result = " << value << "\n";
}
catch (const std::exception& error) {
std::cerr << "error in calculation: " << error.what() << "\n";
}
catch (...) {
std::cout << "unexpected error\n";
}
return 0;
}