So... I want to create simple HTTP Chunked transfer encoding prototype. I have messages as std::strings. And my server API is all string based... so I wonder how to turn std::string length into hex and than back into string?
So say we had std::string("This is the data in the first chunk\r\n").length() that would return say int 37. I want to convert it into hex 0x25 and than to get out from that hex std::string("25"). How to do such thing (using stl and boost)?
#include <sstream>
#include <iomanip>
#include <iostream>
int main() {
// To string:
std::ostringstream oss;
oss << std::hex << 37;
std::string result = oss.str();
std::cout << result << '\n';
// Back from string (if you need it):
std::istringstream iss(result);
int original;
if (!(iss >> std::hex >> original)) {
// handle error here
} else {
std::cout << original << '\n';
}
}
std::stringstream buffer;
buffer << std::hex << your_number;
buffer.str() will now give you a hex-representation of your number; If you want the 0x before the number, use this:
buffer << std::hex << showbase << your_number;
#include <sstream>
#include <iomanip>
std::ostringstream str;
str << "0x" << std::hex << length;
std::string result = str.str();
Demonstrated here.
Stringstreams are one way:
std::ostringstream ss;
ss << "0x" << std::hex << 12345;
std::string aString = ss.str();
An alternative is the all-mighty boost::format.
This would be a solution:
std::string convert_length_to_hex(const std::string& str)
{
std::ostringstream result;
result << std::hex << str.length();
return result.str();
}
Here is my example of dec to hex conversion and then back
#include <iostream>
#include <sstream>
#include <string>
#include <algorithm>
std::string dec2hex(int dec){
std::string result;
std::stringstream ss;
ss << std::hex << dec;
ss >> result;
std::transform(result.begin(), result.end(), result.begin(), ::toupper);
return result;}
int hex2dec(std::string& hex){
int x;
std::stringstream ss;
ss << std::hex << hex;
ss >> x;
return x;
}
int main()
{
std::string hex = "ABCD";
int dec = hex2dec(hex);
std::cout << dec << std::endl;
std::cout << dec2hex(dec) << std::endl;
return 0;
}
