The idea is to have a vector containing arbitrary binary data and outputting the bytes it contains to stdout in hexadecimal notation. I use std::copy to copy the bytes from the input vector to stdout. The problem is that the code prints out 0 followed by raw binary data. Here is the code:
auto vec = std::vector<uint8_t> {'h', 'e', 'l', 'l', 'o'};
std::cout << std::hex << std::setfill('0') << std::setw(2);
std::copy(vec.begin(), vec.end(), std::ostream_iterator<uint8_t>(std::cout));
The application prints out "0hello". I would expect it to print out "68656C6C6F". What can be the case?
Simple change, use int instead of uint8_t:
std::copy(vec.begin(), vec.end(), std::ostream_iterator<int>(std::cout));
If you want it in uppercase, use std::uppercase.
operator<< has non-member overloads for char, signed char, and unsigned char. See: uint8_t iostream behavior.