Byte to bit conversion without bitset from the standard library.

byte_to_bits.cpp

#include <iostream>

using std::cout, std::endl, std::string;

string byte_to_bits(uint8_t byte);

char bool_to_char(bool b);

int main() {
    for (int n = 0; n < 256; n++) {
        cout << byte_to_bits((uint8_t) n) << endl;
    }

    return 0;
}

string byte_to_bits(uint8_t byte) {
    string s;

    for (int i = 0; i < 8; i++) {
        s.push_back(bool_to_char((bool) ((byte << i) & 128)));
    }

    return s;
}

char bool_to_char(bool b) {
    return b ? '1' : '0';
}