Seg Fault using stacks and queues - c++

Question

I am new to using stacks and queues and I am having memory problems. Could you give me a little insight in what I am doing wrong? This is supposed to be an implementation of a war game using stacks and queues.
#ifndef WAR_H
#define WAR_H
/*
This runWar function runs a game of war between 2 automated players
and returns the number of rounds (both put a card down
once per round) until someone won. An integer is given
as an upper limit to how many rounds a game can go on for.
*/
#include <iostream>
#include <stdlib.h>
#include <stdexcept>
#include <stack>
#include <queue>
#include "deck.h"
using namespace std;
int decide(Card, Card, unsigned int&);
int runWar(unsigned int limit)
{
Deck d;
queue<Card> p1;
queue<Card> p2;
while(d.size() != 0)
{
p1.push(d.getTopCard());
if(d.size() != 0)
{
p2.push(d.getTopCard());
}
}
bool winner = false; //checks if anyone won
unsigned int roundcount = 0; //checks number of comparisons
while(roundcount<limit && winner == false)
{
Card one = p1.front();
Card two = p2.front();
p1.pop();
p2.pop();
if(one.getRank() > two.getRank())
{
roundcount++;
p1.push(one);
p1.push(two);
}
else if(one.getRank() < two.getRank())
{
roundcount++;
p2.push(one);
p2.push(two);
}
else
{
stack<Card> pile;
//3 cards off the top each
bool war_done = false;
while(war_done == false)
{
for(unsigned int w=0; w<3; w++)
{
pile.push(p1.front());
pile.push(p2.front());
p1.pop();
p2.pop();
}
Card p11 = p1.front();
Card p22 = p2.front();
pile.push(p11);
pile.push(p22);
p1.pop();
p2.pop();
if(p11.getRank() > p22.getRank())
{
roundcount++;
while(!(pile.empty()))
{
p1.push(pile.top());
pile.pop();
}
p1.push(one);
p1.push(two);
war_done = true;
}
else if(p11.getRank() > p22.getRank())
{
roundcount++;
while(!(pile.empty()))
{
p2.push(pile.top());
pile.pop();
}
p2.push(one);
p2.push(two);
war_done = true;
}
}
if(p1.empty() || p2.empty())
{
winner = true;
}
}
}
return roundcount;
}
#endif
int main()
{
for(unsigned int i=0; i<19; i++)
{
cout<<runWar(1000)<<endl;
}
return 0;
}
My card and deck classes work find. getTopCard() is basically a pop that returns the top card. getRank() says if it is a 2-Ace. Also, the int main() is in the driver.cpp file.
Valgrind Output:
==3942== Memcheck, a memory error detector
==3942== Copyright (C) 2002-2013, and GNU GPL'd, by Julian Seward et al.
==3942== Using Valgrind-3.10.0.SVN and LibVEX; rerun with -h for copyright info
==3942== Command: ./doWar
==3942==
==3942== Conditional jump or move depends on uninitialised value(s)
==3942== at 0x4023BA: runWar(unsigned int) (war.h:77)
==3942== by 0x4016F6: main (doWar.cpp:18)
==3942==
==3942== Conditional jump or move depends on uninitialised value(s)
==3942== at 0x40201B: runWar(unsigned int) (war.h:45)
==3942== by 0x4016F6: main (doWar.cpp:18)
==3942==
==3942== Use of uninitialised value of size 8
==3942== at 0x401FCD: runWar(unsigned int) (war.h:41)
==3942== by 0x4016F6: main (doWar.cpp:18)
==3942==
==3942== Invalid read of size 4
==3942== at 0x401FCD: runWar(unsigned int) (war.h:41)
==3942== by 0x4016F6: main (doWar.cpp:18)
==3942== Address 0x0 is not stack'd, malloc'd or (recently) free'd
==3942==
==3942==
==3942== Process terminating with default action of signal 11 (SIGSEGV)
==3942== Access not within mapped region at address 0x0
==3942== at 0x401FCD: runWar(unsigned int) (war.h:41)
==3942== by 0x4016F6: main (doWar.cpp:18)
==3942== If you believe this happened as a result of a stack
==3942== overflow in your program's main thread (unlikely but
==3942== possible), you can try to increase the size of the
==3942== main thread stack using the --main-stacksize= flag.
==3942== The main thread stack size used in this run was 8388608.
==3942==
==3942== HEAP SUMMARY:
==3942== in use at exit: 1,728 bytes in 6 blocks
==3942== total heap usage: 33 allocs, 27 frees, 8,952 bytes allocated
==3942==
==3942== LEAK SUMMARY:
==3942== definitely lost: 0 bytes in 0 blocks
==3942== indirectly lost: 0 bytes in 0 blocks
==3942== possibly lost: 0 bytes in 0 blocks
==3942== still reachable: 1,728 bytes in 6 blocks
==3942== suppressed: 0 bytes in 0 blocks
==3942== Rerun with --leak-check=full to see details of leaked memory
==3942==
==3942== For counts of detected and suppressed errors, rerun with: -v
==3942== Use --track-origins=yes to see where uninitialised values come from
==3942== ERROR SUMMARY: 31 errors from 4 contexts (suppressed: 0 from 0)
Segmentation fault (core dumped)

Answer 1

Before every 'pop()' check wheather it is empty or not like
If(!p1.empty()){
p1.pop();
}