variable being used without being initialized

[Cutegun]

Hey, newbie here.

I'm trying (unsuccessfully) to write a rock, paper, scissors, lizard, spock game.
So far it keeps coming up:
'Run-Time Check Failure #3 - The variable 'userchoice' is being used without being initialized."
Where is this error taking place and how do I initialized an input variable that is being used with a pseudo number generator?

Can anyone see what I'm doing wrong?

int main()
{
char userchoice;

cout<<"Would you like to play a game?"<<endl; // introducing the game

cout <<"Choose (r)rock, (p)paper, (sc)scissors, (l)lizard, or (sp)spock:"<< userchoice << endl; //user options
cin>> userchoice;


cout<<"The computer choices:";
srand((unsigned) time(0));


int computerchoice;

computerchoice = (rand() % 5) + 1; // random variable and range
cout << fixed <<setprecision(1)<<computerchoice<<endl;

if(computerchoice ==1) // 1 is equal to rock

{
if(userchoice == 'r')
{
cout<<"Rock"<< endl;
cout<<"Tie game"<<endl;
}

else if (userchoice == 'l')
{
cout<<"Rock"<< endl;
cout <<"Rock crushes Lizard. You lose."<< endl;
}

else if (userchoice == 'sc')
{
cout<<"Rock"<< endl;
cout<<"Rock crushes sissors. You lose."<< endl;
}

else if (userchoice == 'p')
{
cout<<"Rock"<< endl;
cout<< "Paper covers rock. You win"<<endl;
}

else if (userchoice == 'sp')
{
cout<<"Rock"<< endl;
cout<<"Spock vaporizes rock. You win"<<endl;
}
}
// ending rock if statements

else if(computerchoice == 2) // 2 is equal to scissors

{

if (userchoice == 'sc')
{
cout<<"Scissors"<< endl;
cout<<"Tie game"<<endl;
}

else if (userchoice == 'l')
{
cout<<"Scissors"<< endl;
cout <<"Scissors cuts the head off of Lizard. You lose."<< endl;
}

else if(userchoice == 'r')
{
cout<<"Scissors"<< endl;
cout<<"Rock crushed scissors. You win."<< endl;
}

else if(userchoice =='p')
{
cout<<"Scissors"<< endl;
cout<< "Scissors cut paper. You lose"<<endl;
}

else if(userchoice == 'sp')
{
cout<<"Scissors"<< endl;
cout <<"Spock crushes scissors. You win"<<endl;
}
} //ending scissor if statments


else if(computerchoice == 3) // 3 is equal to Paper
{
if (userchoice == 'p')
{
cout<<"Paper"<< endl;
cout<<"Tie game"<<endl;
}

else if(userchoice == 'l')
{
cout<<"Paper"<< endl;
cout <<"Lizard eats paper. You win."<< endl;
}

else if(userchoice == 'r')
{
cout<<"Paper"<< endl;
cout<<"Rock crushed Paper. You lose."<< endl;
}

else if(userchoice == 'sc')
{
cout<<"Paper"<< endl;
cout<< "Scissors cut paper. You win"<<endl;
}

else if (userchoice == 'sp')
{
cout<<"Paper"<< endl;
cout <<"Paper disproves Spock. You lose"<<endl;
}
} //ending paper if statements

else if(computerchoice == 4) // 4 is equal to Lizard
{
if (userchoice == 'l')
{
cout<<"Lizard"<< endl;
cout<<"Tie game"<<endl;
}
else if (userchoice == 'p')
{
cout<<"Lizard"<< endl;
cout <<"Lizard eats paper. You lose."<< endl;
}
else if (userchoice == 'r')
{
cout<<"Lizard"<< endl;
cout<<"Rock crushed Lizard. You win."<< endl;
}
else if (userchoice == 'sc')
{
cout<<"Lizard"<< endl;
cout<< "Scissors cut Lizard. You win"<<endl;
}
else if (userchoice == 'sp')
{
cout<<"Lizard"<< endl;
cout <<"Lizard poisons Spock. You lose"<<endl;
}
} //ending Lizard if statements
else if(computerchoice == 5) // 5 is equal to Spock
{
if (userchoice == 'sp')
{
cout<<"Spock"<< endl;
cout<<"Tie game"<<endl;
}
else if (userchoice == 'p')
{
cout<<"Spock"<< endl;
cout <<"Paper disproves Spock. You win."<< endl;
}
else if (userchoice == 'r')
{
cout<<"Spock"<< endl;
cout<<"Spock vaporizes rock. You lose."<< endl;
}
else if (userchoice == 'sc')
{
cout<<"Spock"<< endl;
cout<< "Spock smashes scissors. You lose"<<endl;
}
else if (userchoice == 'l')
{
cout<<"Spock"<< endl;
cout <<"Lizard poisons Spock. You win"<<endl;
}
} //ending Spock if statements

else // if the user did not enter a valid choice
{
cout<<"You did not choose a valid choice"<<endl;
}


system ("pause");
return 0;
}

[zb0S216C]

As the error points out, you need to initialize userchoice( at the top of the main entry-point ) before using it. For example:

int main( )
{
    char userchoice( '\0' );

    // Then the rest of your code...
}

_Wazzak

[Cutegun]

Wow, that was fast. Thank you.

By initializing a char variable ('\0'), will that work with every undefined user input?

Also, I'm having problems when I test the variable options. Mainly sc and sp. The program is not acknowledging them as inputs.

[zb0S216C]

With userchoice being of type char, it can only hold a single character. In order for it to hold multiple characters, consider using string^[1], or char *.

References:
^[1]http://www.cplusplus.com/reference/string/string/


_Wazzak

[DJennings]

Hello Cutegun,

I am a student at UAT, and I am current taking a C++ class. I was browsing the forums and I took an interest in your post. I like your game and would like to offer a suggestion to improve it: the ability to play multiple times. I also took Frameworks advise and changed the userchoice variable to a string.

At the top of your code you should replace:

char userchoice;

cout<<"Would you like to play a game?"<<endl; // introducing the game 

with this:

string userchoice;
int games(0);
int wins(0);
int losses(0);
int ties(0);
int computerchoice(0);

cout<<"How many games would you like to play?"<<endl; // introducing the game
cin >> games;

while (games > 0)
{

NOTE: I also moved the computerchoice variable to the top of the code.

You need to add this to the bottom:

games--;
}

cout << "\nGames Won: " << wins;
cout << "\nGames Lost: " << losses;
cout << "\nGames Tied: " << ties << endl;

In between this:

else // if the user did not enter a valid choice
{
cout<<"You did not choose a valid choice"<<endl;
}

And this:

system ("pause");

And finally you will have to add:
wins++; losses++; ties++;
in each appropriate if or if else statement.

I hope this helps you out. I had fun adding it in.

[zb0S216C]

DJennings, please don't encourage the use of system( ). It's a security risk, and it relies on the Windows operating system, thus rendering the program platform dependent. You can make your own pause method, which may look like this:

void PauseConsole( void )
{
    std::cout << "Press any key to continue..." << std::endl;
    std::cin.get( );
}

_Wazzak

[DJennings]

I only left in the system() command that was in Cutegun's code. Honestly, I did not know that the use of that command was platform dependent. Thanks you for the info, I can use all the pointers I can get.

[kfmfe04]

what you have listed is a C-like implementation (with the exception of iostream), which is fine, but when you are ready to learn more C++, take a look at the implementation below and refactor as much as you like:

disadvantages
- more complex than the C code/harder to understand, initially
- no error checking (I was lazy)
- looks like it's over-engineered

advantages
- when adding new choices, fix in 5 spots, as noted in the comments
- some separation of code vs the engine
- easier to maintain (data driven)
- encapsulation is not too bad
- methods are simple and easy to understand
- you can learn about STL, classes, operators, etc...

please refactor as much as you like - have fun!

One interesting note: I thought I would pump this code out in 10 minutes, but surprisingly, the strict less-than ordering of STL map killed me for a while (simplified on Lines 86-88) - when you use standard objects (like std::string) or plain-old-data (int) as the key, you don't have to worry about it, but once you use your own class, like Combination here, you have to define operator<() very carefully - otherwise, STL map will behave very badly.

Unfortunately, this experience is not unlike many experiences in C++ - I think I will pump out code quickly and then a small implementation detail has to be done correctly, or the project is a fail - that small part takes much longer than the rest.

Programmers who are experienced at C++ will likely look at this code and feel that it's not hard to understand at all. However, other programmers (like L. Torvalds or Pike/Thompson of Go/UNIX fame) will look at this code and say this is why we should use simpler languages!

#include <stdlib.h>

#include <sstream>
#include <iostream>
#include <map>
#include <string>

using namespace std;

// NOTE: need to add entry/entries in FIVE PLACES (1-5 below)
// engine -------------------------------------------------------------- 
enum eCHOICE { kROCK=0, kPAPER, kSCISSORS, kLIZARD, kSPOCK, kMAX };  // 1. add entry
static char charChoices[] = { 'r', 'p', 'X', 'l', 'K' };             // 2. add entry
static const char* strChoices[] = { "Rock", "Paper", "Scissors", "Lizard", "Spock" };  // 3. add entry

class Choice
{
  public:
    Choice( eCHOICE choice ) : m_choice( choice ) { }
    Choice( char choice ) {
      switch( choice ) {
        case 'r': m_choice = kROCK;     break;                       // 4. add entry
        case 'p': m_choice = kPAPER;    break;
        case 'X': m_choice = kSCISSORS; break;
        case 'l': m_choice = kLIZARD;   break;
        case 'K': m_choice = kSPOCK;    break;
      }
    }
      
    static void GetMenu( string& menu ) {
      ostringstream oss;
      oss << "Choose ";
      for ( unsigned i=kROCK; i<kMAX; ++i )
        oss << "(" << charChoices[i] << ")" << strChoices[i] << " ";
      oss << ": ";
      menu = oss.str();
    }

     Choice& operator=( const Choice& rhs ) {
      if ( this==&rhs ) return *this;
      m_choice = rhs.m_choice;
      return *this;
     }

    int intval() const {
      return static_cast<int>( m_choice );
    }

    bool operator==( const Choice& rhs ) const { return m_choice==rhs.m_choice; }

    friend ostream& operator<<( ostream& os, const Choice& rhs ) {
      os << strChoices[ rhs.intval() ];
      return os;
    }

  private:
    eCHOICE m_choice;  
};

struct Combination {
  Combination( const Choice& playerChoice, const Choice& computerChoice ) :
    m_player( playerChoice ), m_computer( computerChoice ) { }

  Combination( const Combination& rhs ) :
    m_player( rhs.m_player ), m_computer( rhs.m_computer ) { }

  Combination reverse() const {
    return Combination( m_computer, m_player );
  }

  Combination& operator=( const Combination& rhs ) {
    if ( this==&rhs ) return *this;
    m_player   = rhs.m_player;
    m_computer = rhs.m_computer;
    return *this;
  }

  int intval() const {
    return m_player.intval() * kMAX + m_computer.intval();
  }

  bool isTied() const {
    return m_player==m_computer;
  }

  bool operator<( const Combination& rhs ) const {
    return intval() < rhs.intval();
  }

  friend ostream& operator<<( ostream& os, const Combination& rhs ) {
    os << "Player="   << rhs.m_player << ", ";
    os << "Computer=" << rhs.m_computer;
    return os;
  }

  Choice m_player, m_computer;
}; 

class Judge {
  public:
    Judge() {
      // 5. add entries in ONE DIRECTION ONLY with Combination( winner, loser ) and proper comments
      m_results[ Combination( kROCK,     kLIZARD )   ] = "Rock crushes Lizard.";
      m_results[ Combination( kROCK,     kSCISSORS ) ] = "Rock crushes Scissors.";
      m_results[ Combination( kPAPER,    kROCK ) ]     = "Paper covers Rock.";
      m_results[ Combination( kPAPER,    kSPOCK ) ]    = "Paper disproves Spock.";
      m_results[ Combination( kSPOCK,    kROCK ) ]     = "Spock vaporizes Rock.";
      m_results[ Combination( kSPOCK,    kSCISSORS ) ] = "Spock smashes Scissors.";
      m_results[ Combination( kSCISSORS, kLIZARD ) ]   = "Scissors cuts the head off of Lizard.";
      m_results[ Combination( kSCISSORS, kPAPER ) ]    = "Scissors cuts Paper.";
      m_results[ Combination( kLIZARD,   kPAPER ) ]    = "Lizard eats Paper.";
      m_results[ Combination( kLIZARD,   kSPOCK ) ]    = "Lizard poisons Spock.";
    }

    void getResultFor( string& result, const Combination& combo )
    {
      if ( combo.isTied() ) {
        result = "Tie game.";
      } else {
        map< Combination, string >::const_iterator it;
        if ( (it=m_results.find( combo ))!=m_results.end() ) {
          result = it->second + " You win!";
        } else if ( (it=m_results.find( combo.reverse() ))!=m_results.end() ) {
          result = it->second + " You lose!";
        } else {
          cerr << "ERROR IN PROGRAM - could not find " << combo << " or " << combo.reverse() << endl;
        }
      }
    }

  private:
    map< Combination, string > m_results;
};

// main ---------------------------------------------------------------- 
int main()
{
  string menu;
  char userchoice;

  Choice::GetMenu( menu );
  cout << menu << endl;  
  cin >> userchoice;

  srand((unsigned) time(0));
  int computerchoice = (rand() % kMAX);

  Choice userChoice(     userchoice );
  Choice computerChoice( charChoices[ computerchoice ] );

  cout << "You chose           :  " << userChoice     << endl; 
  cout << "The computer chooses:  " << computerChoice << endl;

  // -------------------------------------------------------------------
  Judge       judge;
  string      result;
  Combination combo( userChoice, computerChoice );
  judge.getResultFor( result, combo );
  cout << result << endl;;

  return 0;
}

[Cutegun]

Wow, thanks guys.
This is still above the level that I'm at, but it clears up a lot of question.