CODEWITHSUNDEEP
c++booleanbytebit
y2k
y2k

Reputation: 65996

Translate bools to bit sequence

Looking for some operator (I'm guessing in place of + ?) that will do

unsigned char bits = true + false + true + true + true;  // 1 byte is sufficient

to become to following bit pattern:

00010111

Then how can I check that bit pattern in an if

if (bits == 00010111)

Upvotes: 1

Views: 130

Answers (4)

Rapptz
Rapptz

Reputation: 21317

You can use std::bitset's string constructor.

#include <bitset>
#include <string>
#include <iostream>

int main() {
    std::string bits;
    bits.push_back('1');
    bits.push_back('0');
    bits.push_back('1');
    bits.push_back('1');
    bits.push_back('1');
    std::bitset<8> bitset(bits);
    std::cout << bitset.to_string();

}

There are better ways of doing this though.

Upvotes: 3

doug65536
doug65536

Reputation: 6771

The operator + would need to do a shift left by one bit of the current value, then "bitwise OR" the incoming true or false and return that.

This is a quickie implementation I came up with:

#include <iostream>
class Foo
{
    int result;

public:
    Foo() : result(0) {}
    Foo(bool value) : result(value ? 1 : 0) {}
    explicit Foo(int value) : result(value) {}
    Foo operator+(bool value) const
    {
        std::cout << "adding " << value << std::endl;
        return Foo((result << 1) | (value ? 1 : 0));
    }
    int get_result() const { return result; }
};

int main()
{
    Foo x;
    x = Foo(true) + false + true;
    std::cout << x.get_result() << std::endl;
}

Play around with it here

Upvotes: 2

Udo Klein
Udo Klein

Reputation: 6882

you want

bits = true << 5 | false << 4 | true << 3 | true << 2 | true << 1;

or

bits |= true;
bits <<= 1;
bits |= false;
bits <<= 1;
bits |= true;
bits <<= 1;
bits |= true;
bits <<= 1;
bits |= true;

Upvotes: 6

Ed Heal
Ed Heal

Reputation: 59987

Why not use bitset. There is a method to set various bits and to convert to a unsigned long. Just do an & operator on that to get the byte.

Upvotes: 2

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