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Full Discussion: C++/ROOT Memory Allocation?
Top Forums Programming C++/ROOT Memory Allocation? Post 302802791 by Tyler_92 on Saturday 4th of May 2013 11:27:31 PM
Old 05-05-2013
C++/ROOT Memory Allocation?

Hello,
I am new to C++ programming, so I'm still getting a feel for things. I recently wrote a simple C++ program (to be used as a ROOT Macro) to conduct a statistical analysis of a varied version of the Monty Hall problem (code below). Basically, the programs runs a few simple calculations to decide the winner, nothing too complex, and is designed to be run many times for a statistical analysis. What I have noticed is the program uses memory VERY inefficiently. Using Mac Activity Monitor, I notice that when I just loop through 10,000 times my free memory loses ~0.5 gigabytes. This is a program that I want to be able to run at least a million times if not more. Is there some basic error in my code that is causing this? Thanks in advance.
Code:
#include "stdint.h"
#include "TMath.h"
#include <cmath>
#include <TRandom1.h>
#include <iostream>

//Varied Monty Hall Program!

//Function to return a random number to serve as a pointer in the 'door_array' array
int RandomDoor(int& doors)
{
    TRandom1 *myran=new TRandom1(0,389);
    int returnVal=myran->Rndm()*doors;
    return returnVal;
}

//Function to Search for an available door
int Search(int* array,int& doors,int& choosedoor,int& host_doors)
{
    int returnVal;
    if ((doors-host_doors)==1) {
        returnVal=choosedoor;
    }
    
    int rNum=RandomDoor(doors);
    if ((array[rNum]==2)||(rNum==choosedoor)) {
        rNum=RandomDoor(doors);
        while ((array[rNum]==2)||(rNum==choosedoor)) {
            if ((rNum==(doors-1))&&(array[rNum]==2)) {
                rNum=0;
            }
            if ((rNum==(doors-1))&&(rNum==choosedoor)) {
                rNum=0;
            }
            else
            {
                rNum++;
            }
        }
        returnVal=rNum;
    }
    returnVal=RandomDoor(doors);
    return returnVal;
}

void MontyHall2(int doors, long iterations, int host_doors)
{
    double host_wins=0;
    double wins=0;
    double winpct=0;
    //generate array
    int* door_array=new int[doors];
    
    //loop through game 'iteratons' times
    for (long i=0; i<iterations; i++) {
        
        //populate array with 0's
        
        for (int j=0; j<doors; j++) {
            door_array[j]=0;
        }
        
        //choose winning door
        door_array[RandomDoor(doors)]=1;
        
        //player randomly chooses
        
        int choosedoor=RandomDoor(doors);
        
        //Host randomly chooses doors and turns them to "2"
        
        bool rightVal=false;
        for (int k=0; k<host_doors; k++) {
            int temp=Search(door_array,doors,choosedoor,host_doors);
            door_array[temp]=2;
            if (door_array[temp]==1) {
                rightVal=true;
            }
        }
        
        //If host chooses correctly, host_wins++ and game over
        if (rightVal==true) {
            host_wins++;
        }
        
        else {
            
            //Player switches doors
            int limit;
            if (host_doors>3) {
                limit=host_doors/3;
            }
            else {
                limit=1;
            }
            
            bool playerwins=false;
            for (int n=0; n<limit; n++) {
                if (door_array[Search(door_array,doors,choosedoor,host_doors)]==1) {
                    playerwins=true;
                }
            }
            if (playerwins==true) {
                wins++;
            }
        }
    }
    winpct=(100*wins)/iterations;
    cout<<winpct<<" %"<<endl;
    delete[] door_array;
}

 

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HADD(1) 						      General Commands Manual							   HADD(1)

NAME
hadd - Merge ROOT histogram files into one file SYNOPSIS
hadd outputfile inputfiles ... DESCRIPTION
This program will add histograms from a list of ROOT files and write them to a target ROOT file. The target file is newly created and must not be identical to one of the source files. SEE ALSO
root(1) For extensive documentation on the ROOT system, see http://root.cern.ch <http://root.cern.ch> A Users Guide is available from here. <http://root.cern.ch/root/UsersGuide.html> The classes of ROOT are all documented by the automatic documentation system, and is available online. <http://root.cern.ch/root/html/ClassIndex.html> ORIGINAL AUTHORS
Sven A. Schmidt sven.schmidt@cern.ch, Dirk Geppert, and Rene Brun Rene.Brun@cern.ch COPYRIGHT
This library is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2.1 of the License, or (at your option) any later version. This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details. You should have received a copy of the GNU Lesser General Public License along with this library; if not, write to the Free Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA AUTHOR
This manual page was written by Christian Holm Christensen <cholm@nbi.dk>, for the Debian GNU/Linux system (but may be used by others). ROOT
Version 3 HADD(1)
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