我正在尝试动态制作2D数组，然后应该对其进行迭代以检查其内容。每当我尝试使用为数组建立索引的函数时，都会出现分段错误。造成问题的两个函数是printg（）和get（）函数。我不确定自己到底在做什么错，但是它们都不适合我。
任何帮助都会很棒。谢谢。
#ifndef _GRID_H
#define _GRID_H
#include <iostream>
using namespace std;
class Grid
{
public:
Grid();
Grid(const Grid& g2);
Grid(int x, int y, double density);
Grid(string file);
~Grid();
bool check(int x, int y); //check if a cell is inhabited or not
bool isEmpty();//check if a grid is living
bool equals(const Grid& g2);//checks if two grids are equal
void kill(int x, int y);//kill a cell
void grow(int x, int y);//grow a cell
int getSize();
int getNumRows();
int getNumCol();
int getNumLiving();
void printg(int r, int c);
char get(int x, int y) const;
private:
int size; //number of cells in grid
int row; //row length (number of columns)
int column; //column length (number of rows)
int num_living; //number of X's in the grid
char** myGrid;
};
#endif
#include "Grid.h"
#ifndef _GRID_C
#define _GRID_C
#include <iostream>
#include <cmath>
#include <fstream>
#include <cstdlib>
//compile with g++ -I /home/cpsc350/GameOfLife Grid.cpp
using namespace std;
Grid::Grid() //do i need a default constructor????
{
char myGrid[10][10] = {{0,1,2,3}, {4,5,6,7}, {8,9,10,11}};
row = 10;
column = 10;
size = 100;
}
Grid::Grid(const Grid& g2)//copy constructor/////////////help
{
size = g2.size;
row = g2.row;
column = g2.column;
num_living = g2.num_living;
char** myGrid = new char*[row];
for(int i = 0; i < row; i++)
myGrid[i] = new char[column];
for(int i1 = 0; i1 < row; i1++)
{
for(int i2 = 0; i2 < column; i2++)
{
//copy(&g2[i1][i2], &g2[i1][i2]+row*column,&myGrid[i1][i2]);
myGrid[i1][i2] = g2.get(i1,i2);
}
}
}
Grid::Grid(int x, int y, double density)
{
char** myGrid = new char*[x];
for(int i = 0; i < x; i++)
myGrid[i] = new char[y];
row = x;
column = y;
size = x*y;
num_living = size * density;
string str = "";
for(int a = 0; a < num_living; a++)//adds the density of X's to a string
{
str += 'X';
}
for(int a = 0; a < size - num_living; a++)//adds the rest to the string
{
str += '-';
}
int randnum;
//randomly generates indicies in the string str and puts them into the array
for(int i1 = 0; i1 < column; i1++)
{
for(int i2 = 0; i2 < row; i2++)
{
//generate random numbers from index 0 to length of string - 1
if(str.length()>1)
{
randnum = (rand()%(str.length()-1))+1;
}
else
{
randnum = 0;
}
myGrid[i1][i2] = str[randnum];
str.erase(randnum);
}
}
}
Grid::Grid(string file)
{
num_living = 0;
//code to create a 2d array from a filepath
ifstream openfile(file);
//error handling
if(! openfile)
{
cout << "Error, file could not be opened" << endl;
exit(0);
}
openfile >> column;//gets number of rows
openfile >> row;//gets number of columns
size = row*column;
char** myGrid = new char*[row];
for(int i = 0; i < row; i++)
myGrid[i] = new char[column];
for(int x = 0; x<column; x++)
{
for(int y = 0; y<row; y++)
{
openfile >> myGrid[x][y];
if(! openfile)//error handling
{
cout << "Error reading file at " << row << "," << column << endl;
}
if(myGrid[x][y] == 'X')
{
num_living++;
}
}
}
openfile.close();
}
Grid::~Grid()
{
if(myGrid)
{
for(int i = 0; i < row; i++)
{
delete []myGrid[i];
}
delete []myGrid;
}
}
void Grid::kill(int x, int y)
{
if(myGrid[x][y] == 'X')
{
num_living--;
}
myGrid[x][y] = '-';
}
void Grid::grow(int x, int y)
{
if(myGrid[x][y] == '-')
{
num_living++;
}
myGrid[x][y] = 'X';
}
bool Grid::check(int x, int y)
{
if(y<0 || x<0)
{
return(false);
}
return (myGrid[x][y] == 'X');
}
bool Grid::isEmpty()
{
return (num_living == 0);
}
bool Grid::equals(const Grid& g2)
{
if(size != g2.size) //checks if sizes are equal
{
return false;
}
if(row != g2.row)//checks if numRows are equal
{
return false;
}
if(column != g2.column)//checks if numCol are equal
{
return false;
}
if(num_living != g2.num_living)//checks if numliving are equal
{
return false;
}
for(int x = 0; x < row; x++)//checks each element
{
for(int y = 0; y < column; y++)
{
if(myGrid[x][y] != g2.get(x,y))
{
return false;
}
}
}
return true;
}
int Grid::getSize()
{
return(size);
}
int Grid::getNumRows()
{
return(column);
}
int Grid::getNumCol()
{
return(row);
}
int Grid::getNumLiving()
{
return(num_living);
}
void Grid::printg(int r, int c)
{
for(int x = 0; x < r; x++)
{
for(int y = 0; y < c; y++)
{
cout << myGrid[x][y];
}
cout << endl;
}
}
char Grid::get(int x, int y) const
{
return myGrid[x][y];
}
#endif
答案 0 :(得分：0)
我最初看到的问题是您的默认构造函数和复制构造函数均未初始化myGrid。您在它们中所做的将创建一个名为“ shadows” myGrid的同名数组。相反，您必须这样做：
Grid::Grid(const Grid& g2)
{
size = g2.size;
row = g2.row;
column = g2.column;
num_living = g2.num_living;
myGrid = new char*[row]; // removed "char**" at the start of this line
for(int i = 0; i < row; i++)
myGrid[i] = new char[column];
for(int i1 = 0; i1 < row; i1++)
{
for(int i2 = 0; i2 < column; i2++)
{
//copy(&g2[i1][i2], &g2[i1][i2]+row*column,&myGrid[i1][i2]);
myGrid[i1][i2] = g2.get(i1,i2);
}
}
}
您的默认构造函数具有相同的问题。但请注意，您不能使用花括号将其初始化。但是如果您不使用默认构造函数，则不必使用它。