Converting from python to C++ help

[demetri90]

So for my final you have to make a class with various card methods, but I have already made the program last semester but in Python. So I'm just going to rewrite it all in C++, however I need some help on a few things. My biggest area of concerns are the methods in the class, as it involves array syntax I don't know how I should write in C++. Also unsure about all the (self), and the __.

My original Python code:

#This is a class that contains methods for various card game actions. Methods include
#resetting, shuffling, and cutting decks.


class deck:
#Constructor
def __init__(self):
self.__cards = []
self.resetdeck()

#Method that resets the deck
def resetdeck(self):
del self.__cards[0:]
for suit in range(1,5):
for value in range(1,14):
self.__cards.append(str(value)+"|"+str(suit))

#Method that shuffles the deck
def shuffle(self):
random.shuffle(self.__cards)

#Method that cuts the deck
def cutdeck(self):
cutdeck1 = self.__cards[:26]
cutdeck2 = self.__cards[26:]
self.__cards = cutdeck2 + cutdeck1

#Method that cuts to a card
def cuttocard(self):
self.cutdeck()
print self.__cards[-1]

#Method that both CPU and user cut to card and highest card wins
def cutCPU(self):
playerTop = self.__cards[-1]
del self.__cards[-1]
compTop = self.__cards[-1]
del self.__cards[-1]
print "Player", "Computer"
print ""
print playerTop," ", compTop

#Method that returns the cards
def get_cards(self):
return self.__cards

#This program gives the user a choice of various actions to be performed with a deck of cards
#Uses the class designed above.


import random

def main():
getcard = deck()
menuloop = 1
#Loop for actions until user decides to exit
while menuloop == 1:
print ""
print "1. Reset the deck"
print "2. Shuffle the deck"
print "3. Cut the deck"
print "4. Cut to a card"
print "5. Cut against the computer"
print "6. Exit the program"
print ""
uM = input("Select a menu option(#): ")
print ""
if uM == 1:
getcard.resetdeck()
print getcard.get_cards()

if uM == 2:
getcard.shuffle()
print getcard.get_cards()

if uM == 3:
getcard.cutdeck()
print getcard.get_cards()

if uM == 4:
getcard.cuttocard()

if uM == 5:
getcard.cutCPU()

#Exit option, ends loop
if uM == 6:
print "BYE"
menuloop = 0

#Secret option, used to show cards
if uM == 7:
print getcard.get_cards()

#Defensive if statement, only accepts #'s 1-7
if uM != 1 and uM != 2 and uM != 3 and uM != 4 and uM != 5 and uM != 6 and uM != 7:
print "Wrong input entered"

main()

And what I have so far:

//This is a class that contains methods for various card game actions. Methods include
//resetting, shuffling, and cutting decks.


#include <iostream>
#include <random>;
using namespace std;

class deck {
public:
    //Constructor
    deck() {
        self.__cards = [];
		self.resetdeck(); }

    //Method that resets the deck
    int resetdeck() {
        del self.__cards[0:];
        for suit in range(1,5):
            for value in range(1,14):
			self.__cards.append(str(value)+"|"+str(suit)); }
               
    //Method that shuffles the deck
    int shuffle() {
		random.shuffle(self.__cards); }

    //Method that cuts the deck    
    int cutdeck() {
        cutdeck1 = self.__cards[:26];
        cutdeck2 = self.__cards[26:];
		self.__cards = cutdeck2 + cutdeck1; }
        
    //Method that cuts to a card
    int cuttocard() {
        self.cutdeck();
			cout << self.__cards[-1]; }

    //Method that both CPU and user cut to card and highest card wins
    int cutCPU() {
        playerTop = self.__cards[-1];
        del self.__cards[-1];
        compTop = self.__cards[-1];
        del self.__cards[-1];
        cout << "Player", "Computer";
        cout << "";
		cout << playerTop," ", compTop; }
            
    //Method that returns the cards
    int get_cards() {
		return self.__cards; }
}
//This program gives the user a choice of various actions to be performed with a deck of cards
//Uses the class designed above.

    


int main() 
{
    deck getcard;
    int menuloop = 1;
	int uM;
    //Loop for actions until user decides to exit
    while (menuloop == 1)
	{
        cout << "";
        cout << "1. Reset the deck";
        cout << "2. Shuffle the deck";
        cout << "3. Cut the deck";
        cout << "4. Cut to a card";
        cout << "5. Cut against the computer";
        cout << "6. Exit the program";
        cout << "";
		cout << "Select a menu option(#): ";
        cin >> uM;
        cout << "";
        if (uM == 1) {
            getcard.resetdeck();
				cout << getcard.get_cards(); }
            
        if (uM == 2) {
            getcard.shuffle();
				cout << getcard.get_cards(); }

        if (uM == 3) {
            getcard.cutdeck();
				cout << getcard.get_cards(); }

        if (uM == 4)
            getcard.cuttocard();

        if (uM == 5)
            getcard.cutCPU();

        //Exit option, ends loop
        if (uM == 6) { 
            cout << "BYE";
				menuloop = 0; }

        //Secret option, used to show cards
        if (uM == 7)
            cout << getcard.get_cards();

        //Defensive if statement, only accepts #'s 1-7
        if (uM != 1 && uM != 2 && uM != 3 && uM != 4 && uM != 5 && uM != 6 && uM != 7)
            cout << "Wrong input entered";
    
	}
}
    

[Stewbond]

I don't know much about python, but I'm guessing that self is similar to this in c++ and that you are trying to access a local member of the class.

Replace self. everywhere in this code with this->. That is the C++ equivalent. However, you could also just delete self. which is more common in C++ as member objects are automatically within scope everywhere in the class (as long as they are declared!).

As for __cards, you need to define that as a private object in the class. Why private? Because you already have get_cards() to access it by the outside world and so it doesn't need to be available to them.

class deck {
public:
    deck()
    //...
private:
    int __cards; // perhaps card __cards; and define a class called "card"
}

Finally, your for loops in resetdeck() aren't c++. Use:

for (int suit = 1; suit < 5; ++suit)
    for (int value = 1; value < 14; ++value)
        this->__cards...

You may need to use another class for the cards if yuou want to do things like append as you do in your resetdeck.

[Shinigami]

You can change
if (uM != 1 && uM != 2 && uM != 3 && uM != 4 && uM != 5 && uM != 6 && uM != 7)
to
if (uM < 1 || uM > 7)

for __cards use vectors. As c++ do not have list like in python
this is wrong __cards = [];

And you need to declare variable cards in class not in it's constructor. Because in constructor it is available to constructor only.

[JLBorges]

Verbatim translation of the Python class:

#include <vector>
#include <string>
#include <algorithm>
#include <random>
#include <sstream>
#include <iostream>

template< typename T > inline std::string str( const T& v )
{
    std::ostringstream stm ;
    stm << '\'' << v << '\'' ;
    return stm.str() ;
}

class deck
{
    public:
        //Constructor
        deck() { resetdeck(); }

        //Method that resets the deck
        void resetdeck()
        {
            _cards.clear() ;
            for( int suit = 1 ; suit < 5 ; ++suit )
                for( int value = 1 ; value < 14 ; ++value )
                  _cards.push_back( str(value) + "|" + str(suit) );
        }

        //Method that shuffles the deck
        void shuffle() { std::random_shuffle( _cards.begin(), _cards.end() ) ; }

        //Method that cuts the deck
        void cutdeck()
        { std::rotate( _cards.begin(), _cards.begin()+_cards.size()/2, _cards.end() ) ; }

        //Method that cuts to a card
        void cuttocard() { cutdeck() ; std::cout << _cards.back() << '\n' ; }

        //Method that both CPU and user cut to card and highest card wins
        void cutCPU()
        {
            std::string playerTop = _cards.back() ;
            _cards.pop_back() ;
            std::string compTop = _cards.back() ;
            _cards.pop_back() ;
            std::cout << "Player Computer" << playerTop << " " << compTop ;
        }

        //Method that returns the cards
        const std::vector<std::string>& get_cards() { return _cards ; }

        private: std::vector<std::string> _cards ;
};

[demetri90]

Holy cow, up until now I didn't know anybody replied, I could have sworn I subscribed to it too. JLborges, I plugged that class in with my main(), had a few errors in my int main(), however I got it to compile and run.

I made a few changes to the class however they didn't work the way I wanted, originally in my python program, when it shuffled or the secret menu option, it would display each element in the array, basically all 52 cards on screen, I added a cout statement to those two methods however they print just two of the cards. Anyway to make them print all?

Here's the program so far:

#include <vector>
#include <string>
#include <algorithm>
#include <random>
#include <sstream>
#include <iostream>

using namespace std;
template< typename T > inline std::string str( const T& v )
{
    std::ostringstream stm ;
    stm << '\'' << v << '\'' ;
    return stm.str() ;
}

class deck
{
    public:
        //Constructor
        deck() { resetdeck(); }

        //Method that resets the deck
        void resetdeck()
        {
            _cards.clear() ;
            for( int suit = 1 ; suit < 5 ; ++suit )
                for( int value = 1 ; value < 14 ; ++value )
                  _cards.push_back( str(value) + "|" + str(suit) );
        }

        //Method that shuffles the deck
        void shuffle() { std::random_shuffle( _cards.begin(), _cards.end() ) ; std::cout << _cards.back(); }

        //Method that cuts the deck
        void cutdeck()
        { std::rotate( _cards.begin(), _cards.begin()+_cards.size()/2, _cards.end() ) ; std::cout << _cards.back(); }

        //Method that cuts to a card
        void cuttocard() { cutdeck() ; }

        //Method that both CPU and user cut to card and highest card wins
        void cutCPU()
        {
            std::string playerTop = _cards.back() ;
            _cards.pop_back() ;
            std::string compTop = _cards.back() ;
            _cards.pop_back() ;
            std::cout << "Player Computer\n\n" << playerTop << " " << compTop ;
        }

        //Method that returns the cards
        const std::vector<std::string>& get_cards() { return _cards ; }

        private: std::vector<std::string> _cards ;
};

int main() 
{
    deck getcard;
    int menuloop = 1;
	int uM;
    //Loop for actions until user decides to exit
    while (menuloop == 1)
	{
        cout << "\n" << "\n";
        cout << "1. Reset the deck" << "\n";
        cout << "2. Shuffle the deck" << "\n";
        cout << "3. Cut the deck" << "\n";
        cout << "4. Cut to a card" << "\n";
        cout << "5. Cut against the computer" << "\n";
        cout << "6. Exit the program" << "\n";
        cout << "" << "\n";
		cout << "Select a menu option(#): ";
        cin >> uM;
        cout << "" << "\n";
        if (uM == 1) {
            getcard.resetdeck();
				getcard.get_cards(); }
            
        if (uM == 2) {
            getcard.shuffle();
				getcard.get_cards(); }

        if (uM == 3) {
            getcard.cutdeck();
				getcard.get_cards(); }

        if (uM == 4)
            getcard.cuttocard();

        if (uM == 5)
            getcard.cutCPU();

        //Exit option, ends loop
        if (uM == 6) { 
            cout << "BYE";
				menuloop = 0; }

        //Secret option, used to show cards
        if (uM == 7)
            getcard.get_cards();

        //Defensive if statement, only accepts #'s 1-7
        if (uM < 1 || uM > 7)
            cout << "Wrong input entered";
    
	}
}

[demetri90]

I do realize I should be cout'ing the get_cards() method, however it gives me errors when I do cout << getcard.get_cards();

[JLBorges]

        //Secret option, used to show cards
        if (uM == 7)
       {
            const std::vector<std::string>& cards = getcard.get_cards() ;
            std::cout << "[ " ;
            for( std::size_t i = 0 ; i < cards.size() ; ++i )
                std::cout << cards[i] <<  ' '  ;
            std::cout << "]\n" ;
        }

[demetri90]

Awesome, everything works great. Question, what does this bit of code do?

template< typename T > inline std::string str( const T& v )
{
    std::ostringstream stm ;
    stm << '\'' << v << '\'' ;
    return stm.str() ;
}

[JLBorges]

It mimics the behaviour of the python built in function str()

Given an object v of some type T, it returns a string (with quotes around it) that would have been printed if this was possible: std::cout << v ;

[demetri90]

Ok, one last thing. For my input validation, I have this code

        //Defensive if statement, only accepts #'s 1-7
        if (uM < 1 || uM > 7)
            std::cout << "Wrong input entered";

However, when I enter a character, like a for example, it will loop endlessly. How can I fix that?

[JLBorges]

Something like this:

int input_int( int minv, int maxv )
{
    while(true)
    {
        std::cout << "enter a number in the interval [" << minv << ',' << maxv << "]: " ;
        int value ;
        if( std::cin >> value && value >= minv && value <= maxv ) return value ;

        std::cerr << "invalid input.\n" ;

        // http://en.cppreference.com/w/cpp/io/basic_ios/clear
        std::cin.clear() ; // clear the error state (if any)

        // http://en.cppreference.com/w/cpp/io/basic_istream/ignore
        std::cin.ignore( 1024, '\n' ) ; // throw away crud in the input buffer
    }
}

And then:

int main()
{
    // ...

    // only accepts #'s 1-7
    int uM = input_int( 1, 7 ) ;

    // ...
}