Question

I convert a character to binary using std::bitset<CHAR_BIT> binary('c');
but this doesn’t work for a string,

std::string str = "MyString";
std::bitset<SIZE_OF_STRING_IN_BITS> binary(str); //Error Exception

what should be the alternative?

Answer 1

You could repeat this action over every character of the string, shifting the bitset by CHAR_BIT to the left every time:

#include <bitset>
#include <string>
#include <iostream>
#include <numeric>
#include <climits>
template<size_t N>
std::bitset<N> string_to_bitset(const std::string& s)
{
    return accumulate(s.begin(), s.end(), std::bitset<N>(),
           [](const std::bitset<N>& l, char r)
           {
               return std::bitset<N>(r) | l<<CHAR_BIT;
           });
}
int main()
{
    std::string str = "MyString";
    const size_t SIZE_OF_STRING_IN_BITS = CHAR_BIT * 8;
    std::bitset<SIZE_OF_STRING_IN_BITS> binary = string_to_bitset<SIZE_OF_STRING_IN_BITS> (str);
    std::cout << binary << '\n';
}

Seeing as the size of the bitset has to be a constant expression, I would go with boost::dynamic_bitset unless this string is a compile-time constant.