[RH1991]

Have been trying to figure this out for school, played around with it and got half of the pattern that i needed, but tried to change some things around and now i get the error message pa5.cpp: In function `void updateRow()':
pa5.cpp:77: error: incompatible types in assignment of `int' to `int[80]'

anyway i was wondering if anyone could give me some hints about what i am doing wrong.

here is the code

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

void setupRow();
void printRow();
void updateRow();
int findNextCellState(int left_neighbor, int cell, int right_neighbor);

const int WIDTH=80;
int row[WIDTH];
int i;

int main()
{
    setupRow();
    printRow();

    for (int i = 0; i < 40; i++)
    {
        updateRow();
        printRow();
    }
}

// The setupRow function creates an initial state for the cellular
// autonoma
void setupRow()
{
    for (int i = 0; i < WIDTH; i++)
    {
        if( i == WIDTH)
          {
           row[i] = 1;
          }
        else
          {
           row[i] = 0;
          }
    }
}

// The printRow function outputs the state of the row to the user.  For
// all
// cells that are 0, it outputs a space (" "), for all cells that are 1,
// it
// outputs a star ("*")
void printRow()
{
   for (int i = 0; i < WIDTH; i++)
   {
       if( row[i] == 0)
        {
          cout << " ";
        }

  }
   cout << endl;
}

// The updateRow function updates the contents of the row after
// calculating
// the next states using the findNextCellState function
void updateRow()
 {
    int temp_row[WIDTH];

    for( i = 0; i < WIDTH; i++)
     {
         temp_row = row[i];
     }

    for ( int i = 0; i < WIDTH; i++)
     {
       int left_neighbor = i-1;
       int cell = i;
       int right_neighbor = i+1;

       if ( left_neighbor > WIDTH)
        {
           left_neighbor = 0;
        }

       if ( right_neighbor > WIDTH)
        {
           right_neighbor = 0;
        }

       row[i] = findNextCellState( temp_row[left_neighbor],
       temp_row[right_neighbor], temp_row[cell]);

     }
}

// The findNextCellState function implements the Rule 30 celular
// autonoma rules.
// The states for this are:
//
// 111 110 101 100 011 010 001 000
//  0   0   0   1   1   1   1   0

int findNextCellState(int left_neighbor, int cell, int right_neighbor)
{
    if (0 == cell)
    {
        if (1 == (left_neighbor + right_neighbor))
        {
            return 1;
        }

 }
        else
        {
            return 0;
        }
    }
    else
    {
        if (1 == left_neighbor)
        {
            return 0;
        }
        else
        {
            return 1;
        }
    }
}

Thanks!

[jimblumberg]

In the following snippet:

   int temp_row[WIDTH];

    for( i = 0; i < WIDTH; i++)
     {
         temp_row = row[i]

You have declared temp_row as an array, but in your loop you try to access this variable as a single integer. You need to tell the compiler which element of this array to assign the value of row[i].

Edit: You should also try to avoid using global variables when ever possible.

Jim

This post has been edited by jimblumberg: 09 October 2011 - 05:56 PM

[RH1991]

Ah thanks that first one was an easy fix but now the real problem I've been having is that when I run the program only half of the correct pattern shows up. I have only been using c++ for a few weeks now and I can't find any resources about this problem in my book or on the net, if anyone can point me in the right direction it would be greatly appreciated!