Question

以下代码给出了以下错误

错误说明： ImageComponent2.exe中0x00DC5D81处的未处理异常：0xC0000005：访问冲突读取位置0xCDCDCDD5。

// ImageComponents

#include <iostream>
#include "Position.h"

using namespace std;

void labelComponents(int size, int **pixel);
void outputImage(int size, int **pixel);

int main(){

int size = 0;

cout << "Enter image size: ";
cin >> size;

int ** pixel = new int *[size + 2];
for (int i = 1; i <= size; i++)
{
    pixel[i] = new int[size + 2];
}

cout << "Enter the pixel array in row-major order:\n";
for (int i = 1; i <= size; i++)
    for (int j = 1; j <= size; j++)
    {
        cin >> pixel[i][j];
    }

labelComponents(size, pixel);
outputImage(size, pixel);


system("pause");
return (0);
}


void labelComponents(int size, int **pixel){
// initialize offsets
Position * offset = new Position[4];
offset[0] = Position(0, 1);   // right
offset[1] = Position(1, 0);   // down
offset[2] = Position(0, -1);  // left
offset[3] = Position(-1, 0);  // up

int numNbr = 4; // neighbors of a pixel position
Position * nbr = new Position(0, 0);
Position * Q = new Position[size * size];
int id = 1;  // component id
int x = 0; // (Position Q)

// scan all pixels labeling components
for (int r = 1; r <= size; r++)      // row r of image
    for (int c = 1; c <= size; c++)   // column c of image
    {
        if (pixel[r][c] == 1)
        {// new component
            pixel[r][c] = ++id; // get next id
            Position * here = new Position(r, c);

            do
            {// find rest of component
                for (int i = 0; i < numNbr; i++)
                {// check all neighbors of here
                    nbr->setRow(here->getRow() + offset[i].getRow());

                    nbr->setCol(here->getCol() + offset[i].getCol());

                    if (pixel[nbr->getRow()][nbr->getCol()] == 1)
                    {// pixel is part of current component
                        pixel[nbr->getRow()][nbr->getCol()] = id;
                        Q[x] = *nbr; 
                        x++;
                    }
                }
                // any unexplored pixels in component?
                *here = Q[x]; // a component pixel
                x--;
            } while (here != NULL);
        } // end of if, for c, and for r
    }
} // end of labelComponents

void outputImage(int size, int **pixel){
cout << "The labeled image is: ";
for (int i = 1; i <= size; i++){
    cout << endl;
    for (int j = 1; j <= size; j++)
        cout << pixel[i][j] << " ";
}
} // end of outputImage

// Position.h

#ifndef POSITION_H
#define POSITION_H

class Position 
{
private:

int row;   // row number of the position
int col;
// column number of the position

public:
Position(); // default
Position( int theRow, int theCol); // parameter
Position(const Position & aPosition); // copy
Position & operator = (const Position & aPosition); // overload =

// overload =

// mutators
void setRow (int r);
void setCol (int c);
//accessors
int getRow() const;
int getCol() const;
}; // end Position

Position::Position()
 {
 setRow(0);
 setCol(0);
 }

 Position::Position(int r, int c)
 {
  setRow(r);
  setCol(c);
 }

Position::Position(const Position & aPosition)
{
setRow(aPosition.row);
setCol(aPosition.col);
}

 Position & Position::operator=(const Position & aPosition)
 {
  this->row=aPosition.row;
  this->col=aPosition.col;
  return(*this);
  }

void Position::setRow(int r)
{
this->row = r;
}
void Position::setCol(int c)
{
this->col = c;
}
int Position::getRow() const
{
return this->row;
}
int Position::getCol() const
{
return this->col;
}

#endif

Answer 1

在C / C ++中，arraw索引从0变为n-1，而不是从1变为n。你所有的for循环都是错误的：

for (int i = 1; i <= size; i++)

必须替换为：

for (int i = 0; i < size; i++)

否则，您可以访问超出范围的size位置的数组。

使用调试器和/或处理较小的代码会使您更容易理解这一点; - ）

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