尝试弄清楚为什么我在此数组指针上使用 delete 时会出错？

正在尝试加载 png 图像，但不确定发生了什么

错误出现在使用delete[] chunks;

代码

typedef struct {
    char r;
    char g;
    char b;
    char a;
} pixel;

class chunk {
public:
    unsigned char length[4];
    unsigned char type[4];
    unsigned char* data;
    unsigned char CRC[4];

    ~chunk()
    {
        delete[] data;
    }
};

class PNG
{
public:
    PNG();
    PNG(std::string filename);
    ~PNG();
    void loadFile(std::string filename);
    pixel* get();
private:
    pixel * img;
    int width;
    int height;
    int bitdepth;
    int colourtype;
    int compressionmethod;
    int filtermethod;
    int interlacemethod;

    unsigned char* data;
    std::ifstream* file;

    int char2int(unsigned char* arr, int start);
};

void PNG::loadFile(std::string filename)
{
    file = new std::ifstream(filename.c_str(), std::ios::in | std::ios::binary);

    size_t size = 0;
    file->seekg(0, std::ios::end);
    size = file->tellg();
    file->seekg(0, std::ios::beg);

    data = new unsigned char[size];
    file->read((char*)data, size);

    /*
    for (int i = 0; i < size; i++) {
    std::cout << std::hex;
    std::cout.width(2);
    std::cout.fill('0');
    std::cout << (int)data[i] << std::endl;
    }
    */

    size_t index = 8; // ignore header
    chunk* chunks = new chunk[size];

    size_t chunkindex = 0;
    while (index < size) {
        for (int i = 0; i < 4; i++) {
            chunks[chunkindex].length[i] = data[index++];
        }
        std::cout << "Size of Chunk " << chunkindex + 1 << ": " << char2int(chunks[chunkindex].length, 0) << std::endl;
        chunks[chunkindex].data = new unsigned char[char2int(chunks[chunkindex].length, 0)];

        for (int i = 0; i < 4; i++) {
            chunks[chunkindex].type[i] = data[index++];
        }

        if (char2int(chunks[chunkindex].length, 0) != 0) {
            for (int i = 0; i < char2int(chunks[chunkindex].length, 0); i++) {
                chunks[chunkindex].data[i] = data[index++];
            }
        }

        for (int i = 0; i < 4; i++) {
            chunks[chunkindex].CRC[i] = data[index++];
        }

        chunkindex++;
    }

    for (int i = 0; i < chunkindex; i++) {
        char name[5];
        for (int j = 0; j < 4; j++) {
            name[j] = chunks[i].type[j];
        }
        name[4] = '\0';

        if (strcmp(name, "IHDR") == 0) {
            std::cout << "FOUND IHDR" << std::endl;
            width = char2int(chunks[i].data, 0);
            height = char2int(chunks[i].data, 4);
            bitdepth = chunks[i].data[8];
            colourtype = chunks[i].data[9];
            compressionmethod = chunks[i].data[10];
            filtermethod = chunks[i].data[11];
            interlacemethod = chunks[i].data[12];

        }
        else if (strcmp(name, "PLTE") == 0) {
            std::cout << "FOUND PLTE" << std::endl;
        }
        else if (strcmp(name, "IDAT") == 0) {
            std::cout << "FOUND IDAT" << std::endl;
        }
        else if (strcmp(name, "IEND") == 0) {
            std::cout << "FOUND IEND" << std::endl;
        }

    }


    std::cout << "Width: " << width << std::endl;
    std::cout << "Height: " << height << std::endl;

    delete[] chunks;
}

错误: 0xC0000005:访问冲突读取位置0xFFFFFFFFFFFFFFFF

最佳答案

将默认构造函数添加到您的 chunk类(class)。

chunk::chunk () {
   data = 0;
}

当你打电话时

    chunk* chunks = new chunk[size];

size对象已创建，所有创建的对象在 data 中都有垃圾数据变量 - 此成员未初始化。当你打电话时

    delete[] chunks;

对于 chunks 的每个对象数组 dtor 被调用，但是当 data未设置成员 - delete[] data是未定义的行为。

data没有为您的 chunks 中的所有对象设置成员array - 查看你的 while 循环:你为 data 分配内存此行的成员

        chunks[chunkindex].data = new unsigned char[char2int(chunks[chunkindex].length, 0)];

但不是针对所有创建的对象，因为在你的 while 循环中每一次迭代 index增加了多次但chunkindex只有一次。当 while 循环被这个条件停止时 index < size , chunkIndex不等于 size这意味着有 block 对象具有单元化 data成员(member)。

关于c++ - 删除类数组指针时出错，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/49189892/