Read a DWORD from a BYTE array

[BrainHijacker]

I have used ReadFile to fill a BYTE buffer. How can I access the first 4 bytes of it as a DWORD?

LPBYTE readBuffer = new BYTE[1024];

I tried some things like this:

if ((DWORD)&readBuffer[0] == NULL) ......

[helios]

*(DWORD *)readBuffer

[liuyang]

The basic idea is to treat the buffer as a pointer to DWORD, and dereference it.

However if you read it from a file, it could be a different story. If the file was created on a different type of machine, it could save the bytes in a different order.

It I recall correctly, in most PC, we store a DWORD (for example 0x12345678) like this:

78 56 34 12

But in some machines, it was saved like

12 34 56 78

[BrainHijacker]

Nice, that works. But I need to write a dword and then a zero-terminated string to the buffer.

The DWORD is easy, the same as reading from it but how do I write a Zstring right after it? (I am using interprocess communication so I'm reading and writing to a byte buffer, if you're curious)

I tried this

*(DWORD *)writeBuffer = RESPONSECODE;
*(char *)writeBuffer+4 = "This is a test...";

[helios]

Use memcpy() or strcpy().

[BrainHijacker]

Thanks, I got it running on the first try with:

strcpy ((char *)writeBuffer+4,"copy successful");

[helios]

Just make sure the destination is always large enough to contain the source.

[BrainHijacker]

Crap, I figured out that I should have used:

*(DWORD *)(writeBuffer+4)

to actually read/write 4 bytes after the start of the buffer. Heh.