fwrite()文件损坏c++

我是c++的新手(从c#迁移过来)，所以我不太确定这里发生了什么。我想做的是从文件中读取图像并将其写入输出文件，但每当我这样做时，文件的部分似乎已经损坏。

我已经检查了内存中的数据，它实际上是匹配的，所以我相信罪魁祸首一定是fwrite()发生了什么，尽管它总是可能只是我做错了什么。

下面是一些示例数据:http://pastebin.com/x0eZin6K

和我的代码:

// used to figure out if reading in one giant swoop has to do with corruption
int BlockSize = 0x200;
// Read the file data
unsigned char* data = new unsigned char[BlockSize];
// Create a new file
FILE* output = fopen(CStringA(outputFileName), "w+");
for (int i = 0; i < *fileSize; i += BlockSize)
{
    if (*fileSize - i > BlockSize)
    {
        ZeroMemory(data, BlockSize);
        fread(data, sizeof(unsigned char), BlockSize, file);
        // Write out the data
        fwrite(data, sizeof(unsigned char), BlockSize, output);
    }
    else
    {
        int tempSize = *fileSize - i;
        ZeroMemory(data, tempSize);
        fread(data, sizeof(unsigned char), tempSize, file);
        // Write out the data
        fwrite(data, sizeof(unsigned char), tempSize, output);
    }
}
// Close the files, we're done with them
fclose(file);
fclose(output);
delete[] data;
delete fileSize;