roman integer class 1.0

Bjarne Stroustrup “Programming Principles and Practice Using C++”
Chapter 10 Exercise 6
Using std_lib_facilities.h by Bjarne Stroustrup.

My project includes the following files:
p377_6_romanIntMain.cpp my main cpp file
p377_6_romanIntClass.h my roman integer class header file

p377_6_romanIntMain.cpp my main cpp file

[code language=”cpp”]
// Philipp Siedler
// Bjarne Stroustrup’s PPP
// Chapter 10 Exercise 6

#include "p377_6_romanIntClass.h"

int main()
try
{
Roman_int r;
r.set_values();
//cout << r;

keep_window_open();
}
catch (runtime_error e) {
cout << e.what() << endl;
keep_window_open();
}
catch (…) {
cout << "Exiting" << endl;
keep_window_open();
}
[/code]

p377_6_romanIntClass.h my roman integer class header file

[code language=”cpp”]
#pragma once
// Philipp Siedler
// Bjarne Stroustrup’s PPP
// Chapter 10 Exercise 6

#include "std_lib_facilities.h"

vector<char> roman_chars = {
‘N’, ‘I’, ‘V’, ‘X’, ‘L’, ‘C’, ‘D’, ‘M’
};

int roman_char_value(char ch) {
switch (ch) {
case ‘N’:
return 0;
case ‘I’:
return 1;
case ‘V’:
return 5;
case ‘X’:
return 10;
case ‘L’:
return 50;
case ‘C’:
return 100;
case ‘D’:
return 500;
case ‘M’:
return 1000;
default:
return -1;
}
}

class Roman_int {
private:
string roman_string;
int roman_int;
public:

Roman_int() {};
Roman_int(string& _roman_string);

void set_values();
string get_string() { return roman_string; }
int get_int() { return roman_int; }
};

ostream& operator<<(ostream& os, Roman_int _roman_int) {
os << "Roman_int conversion:\n"
<< _roman_int.get_string()
<< " equals " << _roman_int.get_int() << endl;
return os;
}

Roman_int::Roman_int(string& _roman_string) {
roman_string = _roman_string;
}

bool read_roman_string(string& _value) {
string _value_temp;
if (cin >> _value_temp) {
_value = _value_temp;
return true;
}
else {
return false;
}
}

bool check_char_validity(string& _value) {
if (_value.size() == 1) {
cout << "Checking validity of roman char… ";
}
else {
cout << "Checking validity of roman chars… ";
}

int size = int(_value.size());
vector<int> invalid_index;

for (int i = 0; i < size; i++) {
int check = 0;
for (int j = 0; j < roman_chars.size(); j++) {
if (roman_chars[j] == _value[i]) {
check++;
}
}
if (check == 0) {
invalid_index.push_back(i);
}
}

if (invalid_index.size() != 0) {
cout << "Invalid char: ";
for (int i = 0; i < invalid_index.size(); i++) {
cout << _value[invalid_index[i]] << " ";
}
cout << endl;
return false;
}
else {
if (_value.size() == 1) {
cout << "Valid roman char." << endl;
return true;
}
else {
cout << "Valid roman chars." << endl;
return true;
}
}
}

bool check_char_count(string& _value) {
cout << "Checking number of roman chars… ";

int size = _value.size();
vector<int> counter(roman_chars.size(), 0);

for (int i = 0; i < size; i++) {
for (int j = 0; j < roman_chars.size(); j++) {
if (_value[i] == roman_chars[j]) {
counter[j]++;
}
}
}

int check = 0;
for (int i = 0; i < roman_chars.size(); i++) {
if (counter[i] > 1 && (roman_chars[i] == ‘V’ || roman_chars[i] == ‘L’ || roman_chars[i] == ‘D’)) {
cout << "Invalid number of " << roman_chars[i] << "." << endl;
check++;
}
else if (counter[i] > 3 && (roman_chars[i] == ‘I’ || roman_chars[i] == ‘X’ || roman_chars[i] == ‘C’ || roman_chars[i] == ‘M’)) {
cout << "Invalid number of " << roman_chars[i] << "." << endl;
check++;
}
}
if (check == 0) {
if (_value.size() == 1) {
cout << "It is a single char." << endl;
}
else {
cout << "Valid number of chars." << endl;
}
return true;
}
else {
return false;
}
}

void deconpose_roman_string(string& _value, int& _digit) {
cout << "Decomposing roman string… ";

int resulting_val = 0;
int size = _value.size();
int check = 0;

//fill vector
vector<int> value_ints;
for (int i = 0; i < size; i++) {
value_ints.push_back(roman_char_value(_value[i]));
}

/*
I placed before V or X indicates one less, so four is IV (one less than five) and nine is IX (one less than ten)
X placed before L or C indicates ten less, so forty is XL (ten less than fifty) and ninety is XC (ten less than a hundred)
C placed before D or M indicates a hundred less, so four hundred is CD (a hundred less than five hundred) and nine hundred is CM (a hundred less than a thousand)
*/

if (size == 1) {
resulting_val = value_ints[0];
}
else {
for (int i = 0; i < size; i++) {
if (_value[i] == ‘I’ && (_value[i + 1] == ‘V’ || _value[i + 1] == ‘X’)) {
if (i == 0 && size == 2) {
resulting_val += (value_ints[i + 1] – value_ints[i]);
i++;
}
else if ((value_ints[i + 1] – value_ints[i]) < resulting_val){
resulting_val += (value_ints[i + 1] – value_ints[i]);
i++;
}
else {
cout << "Number not existing." << endl;
check = 1;
}
}
else if (_value[i] == ‘X’ && (_value[i + 1] == ‘L’ || _value[i + 1] == ‘C’)) {
if (i == 0 && size == 2) {
resulting_val += (value_ints[i + 1] – value_ints[i]);
i++;
}
else if ((value_ints[i + 1] – value_ints[i]) < resulting_val) {
resulting_val += (value_ints[i + 1] – value_ints[i]);
i++;
}
else {
cout << "Number not existing." << endl;
check = 1;
}
}
else if (_value[i] == ‘C’ && (_value[i + 1] == ‘D’ || _value[i + 1] == ‘M’)) {
if (i == 0 && size == 2) {
resulting_val += (value_ints[i + 1] – value_ints[i]);
i++;
}
else if ((value_ints[i + 1] – value_ints[i]) < resulting_val) {
resulting_val += (value_ints[i + 1] – value_ints[i]);
i++;
}
else {
cout << "Number not existing." << endl;
check = 1;
}
}
else {
resulting_val += value_ints[i];
}
}
}

if (check == 0) {
cout << "resulting value = " << resulting_val << endl;
_digit = resulting_val;
}
}

void Roman_int::set_values() {
//while (true) {
cout << "Enter roman string or char:" << endl;
//read roman string from user
if (read_roman_string(roman_string)) {
if (roman_string == "p") {
//break;
}
//check if valid roman chars
//check if valid count of chars
else if (check_char_validity(roman_string) && check_char_count(roman_string)) {
//decompose roman string
deconpose_roman_string(roman_string, roman_int);
cout << "Roman_int conversion:\n"
<< get_string()
<< " equals " << get_int() << endl;
}
}
//}
}
[/code]

Output:
Enter roman string or char:
IV
Checking validity of roman chars... Valid roman chars.
Checking number of roman chars... Valid number of chars.
Decomposing roman string... resulting value = 4
Roman_int conversion:
IV equals 4
Please enter a character to exit

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