Question

Not sure how else to put that, but I’ll start off with a code snippet and output:

uint32_t expires;

cout << "Expiration bytes: " << setfill('0') << hex
     << setw(2) << (unsigned short)rec[keyLen+4]
     << setw(2) << (unsigned short)rec[keyLen+5]
     << setw(2) << (unsigned short)rec[keyLen+6]
     << setw(2) << (unsigned short)rec[keyLen+7] << endl;

expires = ntohl(*(uint32_t*)&rec[keyLen+4]);

cout << "Expiration: " << (long)expires << endl;

cout << "Hex: " << hex << expires << endl;

Outputs:

Expiration bytes: 00000258
Expiration: 258
Hex: 258

I can confirm from other parts of the program that examining and outputting the hex representation of bytes works as expected, and that those are indeed the bytes in the byte stream (sent from another application).

Now, I would be able to understand a bit better if expiration just held some nonsense, because that would mean there’s some egregious error (probably involving pointers). But this… this is clearly just spitting out the hex value as if it were a decimal, and that’s plain wrong.

To make matters more confusing, this works at another point in the program:

fullSize = ntohs(*(uint16_t*)&buff[0]);

With a byte value of 0x0114, fullSize will contain the value 276.

So the question is, what the heck is going on here? How is it possible for an int to be wrong?

Answer 1

cout << "Expiration: " << dec << (long)expires << endl; will output decimal, otherwise the last setting (hex or dec) will still be in effect.