memcpy从数组尾部复制了错误的数据

Question

I have a problem with memcpy function. I tried copy part of data from array of char but I was not success.

// Types
typedef unsigned char BYTE;
typedef unsigned short WORD;
typedef unsigned long DWORD;

// My variables
WORD bfType;
DWORD bfSize;
WORD bfReserved1;
WORD bfReserved2;
DWORD bfOffBits;

// My Func
void BmpFileHeader::setFileHeader(char* header)
{
    // header -> 42 4D BB E6 00 00 00 00 00 00 36 00 00 00
    char* pointerOfHeader = header;
    std::memcpy(&bfType, header, sizeof(WORD));
    pointerOfHeader+=2;
    std::memcpy(&bfSize, pointerOfHeader, sizeof(DWORD));
    pointerOfHeader+=4;
    std::memcpy(&bfReserved1, pointerOfHeader, sizeof(WORD));
    pointerOfHeader+=2;
    std::memcpy(&bfReserved2, pointerOfHeader, sizeof(WORD));
    pointerOfHeader+=2;
    // This point, pointerOfHeader is 36(catched with debugging)
    std::memcpy(&bfOffBits, pointerOfHeader, sizeof(DWORD));
 }

All of my variables take true value except bfOffBits (example 7950260717192478774). I tried to change size but I was not succeed. What is the point I am missing?

Answer 1

It appears as though your compiler is treating unsigned long as a 64-bit quantity, but the Win32 API defines DWORD as an unsigned 32-bit value. Try:

typedef uint32_t DWORD;