c++ - "msvcp90d.dll"中未处理的异常？

Question

我是一个相当新的程序员，所以请多多包涵。我正在使用 VC++ 2008。

我的程序出现这个错误:

Unhandled exception at 0x68bce2ba (msvcp90d.dll) in z projection.exe: 0xC0000005: Access violation writing location 0x00630067.

然后计算机将我带到这一页代码，它看起来相当困惑，而且肯定不是我写的。它指出这部分代码是有问题的代码(标记为“<-computer points to this line”):

public:
_CRTIMP2_PURE static size_t __CLRCALL_OR_CDECL _Getcat(const facet ** = 0,
    const locale * = 0)
{   // get category value, or -1 if no corresponding C category
    return ((size_t)(-1));
}

_CRTIMP2_PURE void __CLR_OR_THIS_CALL _Incref()
{   // safely increment the reference count
    _BEGIN_LOCK(_LOCK_LOCALE)
        if (_Refs < (size_t)(-1))
            ++_Refs;      <-computer points to this line
    _END_LOCK()
}

_CRTIMP2_PURE facet *__CLR_OR_THIS_CALL _Decref()
{   // safely decrement the reference count, return this when dead
    _BEGIN_LOCK(_LOCK_LOCALE)
    if (0 < _Refs && _Refs < (size_t)(-1))
        --_Refs;
    return (_Refs == 0 ? this : 0);
    _END_LOCK()
}

我已经将范围缩小到我自己的程序中可能导致崩溃的代码行(第 4 行代码以“index”开头，也是 stage = 1):

stringstream index;
string fileName = "";
index.str("");//

index << setw( 3 ) << setfill( '0' ) << stage - 1;

fileName = "positive Z topography-" + index.str() + ".txt";

让我感到困惑的是，我从我编写的另一个程序中复制并粘贴了这段代码，该程序已经运行了数百次，从未出现过任何问题。

编辑:这里是完整的代码。

#include <iostream>
#include <fstream>
#include <sstream>
#include <string>
#include <iomanip>

using namespace std;

int main ()
{
    int dim = 100;
    int steps = 9;  //step 0 = 1, steps = actual steps + 1
    int spread = 5; //number of points averaged to get a slope, must be an odd number
    int halfSpread = (spread - 1)/2; //redefine for eazier use in program (better efficency)

    char * partMap = new char [dim * dim * dim]; // cad data

    // positive and negitive denote the x direction the check is moving in. Positive is  0 -> x, negitive is x -> 0.
    unsigned short int * positiveProjection = new unsigned short int [dim * dim]; //projection arrays
    unsigned short int * negitiveProjection = new unsigned short int [dim * dim];

    unsigned short int * negitiveThickness = new unsigned short int [dim * dim];

    double * negitiveXGradient = new double [dim * dim];
    double * negitiveYGradient = new double [dim * dim];

    stringstream index;
    string fileName;

    ifstream txtFile;
    txtFile.open("3D CAD Part.txt");
    txtFile.read(partMap, dim * dim * dim);
    txtFile.close();


    for (int stage = 1; stage < steps; stage++)
    {

        cout << "stage " << stage << endl;

        //z axis projections
        //projection order is along x then along y, during each step, along z in both directions

        int k = 0; // z axis loop variable

        for (int j = 0; j < dim; j++)
        {
            for (int i = 0; i < dim; i++)
            {
                k = 0;

                while ((k != dim) && partMap[dim * ((dim - 1 - k) + dim * i) + j] < stage) 
                    k++;
                positiveProjection[dim * k + j] = k;

                k = dim;

                while ((k != 0) && partMap[dim * ((dim - 1 - (k - 1)) + dim * i) + j] < stage) 
                    k--;
                negitiveProjection[dim * k + j] = i;

                while ((k != 0) && partMap[dim * ((dim - 1 - (k - 1)) + dim * i) + j] >= stage) 
                    k--;
                negitiveThickness[dim * k + j] = negitiveProjection[dim * k + j] - k;
            }
        }

        // negitive dz/dx gradient
        for (int j = 0; j < dim; j++)
        {

            //first loop to handle the first edge gradients
            for (int i = 0; i < halfSpread; i++)
                negitiveXGradient[(j * dim) + i] = (double(negitiveProjection[(j * dim) + halfSpread + i]) - double(negitiveProjection[j * dim]))/(halfSpread + i); // untested

            //second loop to handle the main middle section
            for (int i = halfSpread; i < dim - halfSpread; i++)
                negitiveXGradient[(j * dim) + i] = (double(negitiveProjection[(j * dim) + i + halfSpread]) - double(negitiveProjection[(j * dim) + i - halfSpread]))/ (spread - 1); // untested

            //third loop to handle the end edge gradients
            for (int i = dim - halfSpread; i < dim; i++)
                negitiveXGradient[(j * dim) + i] = (double(negitiveProjection[(j * dim) + dim - 1]) - double(negitiveProjection[j * dim + i - halfSpread]))/((dim - 1) - i + halfSpread); // untested
        }

        // negitive dz/dy gradient
        for (int i = 0; i < dim; i++)
        {
            //first loop to handle the first edge gradients
            for (int j = 0; j < halfSpread; j++)
                negitiveYGradient[(j * dim) + i] = (double(negitiveProjection[((j + halfSpread) * dim) + i]) - double(negitiveProjection[i]))/(halfSpread + j); // untested

            //second loop to handle the main middle section
            for (int j = halfSpread; j < dim - halfSpread; j++)
                negitiveYGradient[(j * dim) + i] = (double(negitiveProjection[((j + halfSpread) * dim) + i]) - double(negitiveProjection[((j - halfSpread) * dim) + i]))/ (spread - 1); // untested

            //third loop to handle the end edge gradients
            for (int j = dim - halfSpread; j < dim; j++)
                negitiveYGradient[(j * dim) + i] = (double(negitiveProjection[(dim * (dim - 1)) + i]) - double(negitiveProjection[((j - halfSpread) * dim) + i]))/((dim - 1) - j + halfSpread); // untested
        }

        fileName = ""; // reset string and stringstream
        index.str("");//

        index << setw( 3 ) << setfill( '0' ) << stage - 1; // set index, index is -1 of stage due to the program structure

        fileName = "positive Z topography-" + index.str() + ".txt";

        ofstream outputFile1(fileName.c_str(), std::ios::binary | std::ios::out);
        outputFile1.write(reinterpret_cast<const char*>(positiveProjection), streamsize(dim * dim * sizeof(unsigned short int)));
        outputFile1.close();

        fileName = "negitive Z topography-" + index.str() + ".txt";

        ofstream outputFile2(fileName.c_str(), std::ios::binary | std::ios::out);
        outputFile2.write(reinterpret_cast<const char*>(negitiveProjection), streamsize(dim * dim * sizeof(unsigned short int)));
        outputFile2.close();

        fileName = "negitive Z thickness-" + index.str() + ".txt";

        ofstream outputFile4(fileName.c_str(), std::ios::binary | std::ios::out);
        outputFile4.write(reinterpret_cast<const char*>(negitiveThickness), streamsize(dim * dim * sizeof(unsigned short int)));    
        outputFile4.close();

        fileName = "negitive Z X gradient-" + index.str() + ".txt";

        ofstream outputFile5(fileName.c_str(), std::ios::binary | std::ios::out);
        outputFile5.write(reinterpret_cast<const char*>(negitiveXGradient), streamsize(dim * dim * sizeof(double)));
        outputFile5.close();

        fileName = "negitive Z Y gradient-" + index.str() + ".txt";

        ofstream outputFile6(fileName.c_str(), std::ios::binary | std::ios::out);
        outputFile6.write(reinterpret_cast<const char*>(negitiveYGradient), streamsize(dim * dim * sizeof(double)));
        outputFile6.close();
    }
}

好的，一切都很好，直到我开始将结果输出到硬盘的最后一段代码。我使用了VC++中的断点和最后一个断点成功通过之前提到的点(我发布的第二个代码块)。显然 HTML 也不喜欢我的 C++ 代码。

哦，另外，省去了遍历循环的麻烦……它们应该没问题……那里有十几个循环，您无需担心其中发生了什么，它们是很安全。我只有最后一 block 有问题。

Answer 1

即使最后一个 block 出现问题并不一定意味着您的循环中没有错误。如果您超出了任何数组的范围，您可能要等到以后才能得到任何指示。

在第一个内部 while 循环中有

while ((k != dim) && partMap[dim * ((dim - 1 - k) + dim * i) + j] < stage) 
    k++;

这意味着当完成 while 循环时，k 可能具有值 dim。下一行然后做

positiveProjection[dim * k + j] = k;

对于任何 j，这将在 positiveProjection 中超出范围，因为您正在尝试使用 dim*dim + j 进行索引，并且它只有维度 dim*dim。