segmentation fault

unstoppy (49)
Hey guys,
I'm trying to make a Game of life. But every time I count neighbours I get segmentation fault, what's the reason behind that?
This is the code that i have written so far.
The problem is in method "calculate", but i'm not able to figure it out.
Thx in advance.


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/*
 * GameOfLife.cpp
 *
 *  Created on: Dec 7, 2011
 *      Author: unstoppy
 */

#include <iostream>
#include <vector>

#include "GameOfLife.h"

using namespace std;

GameOfLife::GameOfLife()  {
	int x = 0;
	int y = 0;

	vector < vector <bool> > v1(0, vector<bool>(0));

	for (int i = 0; i < v1.size(); i++){
		for (int j = 0; j < v1.size(); j++){
			v1[i][j] = false;
			}
		}

//2nd vector

//the start position of glider
	vector < vector <bool> > vect(0, vector<bool>(0));
	for (int i = 0; i < vect.size(); i++){
		for (int j = 0; j < vect.size(); j++){
			vect[i][j] = false;
			}
		}	
	}

GameOfLife::~GameOfLife() {

}

void GameOfLife::print1(vector<vector <bool> > &v){

	for (int i = 0; i < 10; i++){
		for (int j = 0; j < 40; j++){
			if (v[i][j] == true){				
				cout <<" *";
			}
			else{
				cout <<"  ";
			}

			}
		cout <<endl;
		}
	
}



void GameOfLife::calculate(vector<vector <bool> > &v){
	vector < vector <bool> > v1(40, vector<bool>(10));	
	int neighbour = 0;
	for (int m=0; m < v.size(); m++){
		for (int n=0; m < v.size(); n++){
			if (v[m-1][n-1] == true)
					neighbour += 1;
			if (v[m-1][n] == true)
					neighbour += 1;
			if (v[m-1][n+1] == true)
					neighbour  += 1;
			if (v[m][n-1] == true)
					neighbour  += 1;
			if (v[m][n+1] == true)
					neighbour  += 1;
			if (v[m+1][n-1] == true)
					neighbour  += 1;
			if (v[m+1][n] == true)
					neighbour  += 1;
			if (v[m][n+1] == true)
					neighbour  += 1;

			//Applying the rules
			if (v[m][n]==true && (neighbour == 2 || neighbour == 3))
				v1[m][n] = true;

			if (v[m][n]==true && (neighbour > 4 || neighbour < 2))
				v1[m][n] = false;

			if (v[m][n]==false && neighbour == 3)
				v1[m][n] = true;
			}

		}
                 v.swap(v1);
	}

//---------------------------------------------------------------------------------

int main()
{
	GameOfLife glider;
	
	//glider.print1();
	vector < vector <bool> > vec(40, vector<bool>(10));	
	vec[5][1] = true;
	vec[5][2] = true;
	vec[6][1] = true;
	vec[6][2] = true;

	vec[3][13] = true;
	vec[3][14] = true;
	vec[4][12] = true;
	vec[5][11] = true;
	vec[6][11] = true;
	vec[7][11] = true;
	vec[8][12] = true;
	vec[9][13] = true;
	vec[9][14] = true;

	vec[6][15] = true;
	vec[4][16] = true;
	vec[5][17] = true;
	vec[7][17] = true;
	vec[6][17] = true;
	vec[6][18] = true;
	vec[8][16] = true;

	vec[3][21] = true;
	vec[4][21] = true;
	vec[5][21] = true;

	vec[2][23] = true;
	vec[1][25] = true;
	vec[2][25] = true;

	vec[6][23] = true;

	vec[3][35] = true;
	vec[3][36] = true;
	vec[4][35] = true;
	vec[4][36] = true;

	vec[3][22] = true;
	vec[4][22] = true;
	vec[5][22] = true;
	vec[6][25] = true;
	vec[7][25] = true;
	
	

	glider.print1(vec);
	glider.calculate(vec);
	glider.print1(vec);
}
Last edited on
ne555 (10692)
You are accessing out of bounds in the calculate function. (-1 and size)
Either check the borders separately, or make centinels there
unstoppy (49)
thx for ur reply. i'm new to c++. i don't know how to make centinels. can u help me plz?
ne555 (10692)
The idea is simple. Put in the border cells some value that will not affect the calculations.
In this case you could use false

So you create your matrix a little bigger, and you say that the world goes from 1 to size()-1
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//calculate method
	for (int K=1; K+1 < v.size(); ++K){
		for (int L=1; L+1 < v[K].size(); ++L){

By the way, you've got a mistake in line 66. You are checking the condition on the wrong index.
Last edited on
unstoppy (49)

once again thx!

u meant this by line 66?
if (v[m-1][n-1] == true)

i think it has to be checked coz u need to look for all the neighbours which surround the cell.
so if the cell i'm checking is "a11"

[ [a00, a01, a02]
[a10, a11, a12]
[a20, a21, a22]]

I think i have to check all the cells a00 too. am i right?
ne555 (10692)
line 66: for (int n=0; m < v.size(); n++){ Note that you are looping with n but the condition is against m

Yep, the neighbourhood is correct.

By the way, I found obfuscated to write v[m][n] == false. You already have a boolean, so check it directly
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not v[m][n] //replacing ==false
v[m][n] //replacing ==true
Last edited on
unstoppy (49)

thx. line 66 was a stupid mistake by me.
i didnt know before that "not" can be used in place of false statement.
i have edited these codes. but i have tried printing it but i dont think i'm getting the right result yet.
do u have any suggestion how can i display it like an animation? i think i have to use an infinite loop to change from one state to another. 
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/*
 * GameOfLife.cpp
 *
 *  Created on: Dec 7, 2011
 *      Author: unstoppy
 */

#include <iostream>
#include <vector>

#include "GameOfLife.h"

using namespace std;

GameOfLife::GameOfLife()  {
	int x = 0;
	int y = 0;

	vector < vector <bool> > v11(0, vector<bool>(0));

	for (int i = 0; i < v11.size(); i++){
		for (int j = 0; j < v11.size(); j++){
			v11[i][j] = false;
			}
		}

//2nd vector

//the start position of glider
	vector < vector <bool> > vect(0, vector<bool>(0));
	for (int i = 0; i < vect.size(); i++){
		for (int j = 0; j < vect.size(); j++){
			vect[i][j] = false;
			}
		}	
	}

GameOfLife::~GameOfLife() {

}

void GameOfLife::print1(vector<vector <bool> > &v){

	for (int i = 0; i < v.size(); i++){
		for (int j = 0; j < v.size(); j++){
			if (v[i][j] == true){				
				cout <<" *";
			}
			else{
				cout <<"  ";
			}

			}
		cout <<endl;
		}
	
}



void GameOfLife::calculate(vector<vector <bool> > &v){
	vector < vector <bool> > v1(40, vector<bool>(10));	
	int neighbour = 0;
	for (int m=1; m < (v.size()-1); m++){
		for (int n=1; n < (v.size()-1); n++){
			if (v[m-1][n-1] == true)
					neighbour += 1;
			if (v[m-1][n] == true)
					neighbour += 1;
			if (v[m-1][n+1] == true)
					neighbour  += 1;
			if (v[m][n-1] == true)
					neighbour  += 1;
			if (v[m][n+1] == true)
					neighbour  += 1;
			if (v[m+1][n-1] == true)
					neighbour  += 1;
			if (v[m+1][n] == true)
					neighbour  += 1;
			if (v[m][n+1] == true)
					neighbour  += 1;
			
		
			//Applying the rules
			if (v[m][n] && (neighbour == 2 || neighbour == 3))
				v1[m][n] = true;

			if (v[m][n] && (neighbour > 4 || neighbour < 2))
				v1[m][n] = false;

			if (not v[m][n] && neighbour == 3)
				v1[m][n] = true;
			}

		}v.swap(v1);
	}

//---------------------------------------------------------------------------------

int main()
{
	GameOfLife glider;
	
	//glider.print1();
	vector < vector <bool> > vec(40, vector<bool>(10));	
	vec[5][1] = true;
	vec[5][2] = true;
	vec[6][1] = true;
	vec[6][2] = true;

	vec[3][13] = true;
	vec[3][14] = true;
	vec[4][12] = true;
	vec[5][11] = true;
	vec[6][11] = true;
	vec[7][11] = true;
	vec[8][12] = true;
	vec[9][13] = true;
	vec[9][14] = true;

	vec[6][15] = true;
	vec[4][16] = true;
	vec[5][17] = true;
	vec[7][17] = true;
	vec[6][17] = true;
	vec[6][18] = true;
	vec[8][16] = true;

	vec[3][21] = true;
	vec[4][21] = true;
	vec[5][21] = true;

	vec[2][23] = true;
	vec[1][25] = true;
	vec[2][25] = true;

	vec[6][23] = true;

	vec[3][35] = true;
	vec[3][36] = true;
	vec[4][35] = true;
	vec[4][36] = true;

	vec[3][22] = true;
	vec[4][22] = true;
	vec[5][22] = true;
	vec[6][25] = true;
	vec[7][25] = true;

	
	glider.print1(vec);
	glider.calculate(vec);
	glider.calculate(vec);
	glider.calculate(vec);
	
	
	glider.print1(vec);
	
}
Last edited on
ne555 (10692)
Sorry, I explained it badly.
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			if (not v[m][n] && neighbour == 3)
				v1[m][n]; //statement has no effect
			}
You need to set the value there v1[m][n] = true;

I was talking about wheter you check the value.
Remember that comparison == and assignment = are different. The idea was to replace the comparisons.
unstoppy (49)
I understand now. I've edited it. do u have any idea how can i display the iteration. Like this picture: http://upload.wikimedia.org/wikipedia/commons/e/e5/Gospers_glider_gun.gif
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