Getting a buffer into a stringstream in hex representation:

Question

If I had a buffer like:

uint8_t buffer[32]; 

and it was filled up completely with values, how could I get it into a stringstream, in hexadecimal representation, with 0-padding on small values?

I tried:

std::stringstream ss; for (int i = 0; i < 32; ++i) {     ss << std::hex << buffer[i]; } 

but when I take the string out of the stringstream, I have an issue: bytes with values < 16 only take one character to represent, and I'd like them to be 0 padded.

For example if bytes 1 and 2 in the array were {32} {4} my stringstream would have:

204 instead of 2004 

Can I apply formatting to the stringstream to add the 0-padding somehow? I know I can do this with sprintf, but the streams already being used for a lot of information and it would be a great help to achieve this somehow.

Answer 1

#include <sstream> #include <iomanip>  std::stringstream ss; ss << std::hex << std::setfill('0'); for (int i = 0; i < 32; ++i) {     ss << std::setw(2) << static_cast<unsigned>(buffer[i]); }