How can I set a strings value from hex? - c++

Question

for example the text "Book of Summoning"s hex value is "42 6F 6F 6B 20 6F 66 20 53 75 6D 6D 6F 6E 69 6E 67"
so i would want to be able to set the variable as if i set it like string a = "book of summoing";
but using the hex value.
With input like this or something similar.
std::string hex = "42 6F 6F 6B 20 6F 66 20 53 75 6D 6D 6F 6E 69 6E 67";
I want to set a string variable with it so that the string will look like "Book of Summoning";
As if I were to look at this variable in debug mode, each character of the string would have one of these spaced hex values. But of course printing the string would print "Book of Summoning".
if i just new how to do it with one character i could build such a function.
OR if you can do with with decimal instead of hex that will work for me also, as ill just make a function to convert from hex to dec
EDIT:
in the debug mode i can see that the string hex[0] first char 'B' has a 66 beside it, which im guess is the dec value for that character. if i new how to get that value or set a string by setting that value i could do all this but i dont know if i can do that.

Answer 1

Like this:
std::string hex = "42 6F 6F 6B 20 6F 66 20 53 75 6D 6D 6F 6E 69 6E 67";
std::istringstream iss(hex);
int i;
while (iss >> std::hex >> i)
std::cout << static_cast<char>(i);
// alternatively
// s += static_cast<char>(i);
// where s is a std::string
This assumes the input is already sanitized and contains values that fit in a char.
Live demo.

Answer 2

#include <iostream>
#include <iomanip>
#include <sstream>
#include <string>
#include <iterator>
#include <algorithm>
int main()
{
std::string hex = "42 6F 6F 6B 20 6F 66 20 53 75 6D 6D 6F 6E 69 6E 67";
std::istringstream is( hex );
is >> std::hex;
std::copy( std::istream_iterator<int>( is ), std::istream_iterator<int>(),
std::ostream_iterator<char>( std::cout ) );
std::cout << std::endl;
}
EDIT: I added missed header <sstream>

Answer 3

The algorithm:
start traversing the input string
append in a temporary string the current character
at each space you:
convert the temporary string into a temporary number via strtol (or similar - where you can specify the base) using base 16
reset the temporary string to be empty
get the ASCII character for your temporary number
append it to the final string.
Go on as long as you have character in the input string.