CODEWITHSUNDEEP
c++vectorconverters
Toma
Toma

Reputation: 171

c++ convert vector of integers to an integer

was searching the web for an easy guide and couldn't find one.

I build a converter from decimal to binary and have the 1's and 0's saved in a vector. I want now to turn that vector into one integer. I found all kinds of ways (that I didn't really understand) to convert to string and than to integer, can that be avoided? I'd like to keep it as simple as possible.

here is my code:

c.hpp:

#ifndef C_HPP
#define C_HPP
#include <vector>


class Dualrechnung{
private:
    std::vector<int> vec;
    int z = 123456; //Eingegebene Zahl
    int t_z = z; //temp Zahl

public:
    Dualrechnung();
    ~Dualrechnung();
};

#endif

c.cpp:

#include <vector>
#include <cmath>
#include <sstream>
#include "c.hpp"
#include <iostream>


Dualrechnung::Dualrechnung()
{
    int b;
        for (int i=0; (t_z-(pow(2,i))) >= 0; i++) //finds biggest power of 2 in z
        {
            b= i;
        }
        t_z-=pow(2,b); //whats left after the biggest power 
        vec.push_back(1);
    for(int i = b; i > 0; --i) //checks for every power of 2 multiples smaller than b if they exist in z. if they are, saves 1 for that power in the vector and if not, saves 0.
    {
        b--;
        if((t_z-pow(2,b)) >= 0)
            {
                vec.push_back(1);
                t_z-=pow(2,b);
            }
        else{vec.push_back(0);}
    }

// here I'd like that integer with the information from the vector

    int bin; //binary value of z
        std::cout << z << " in Dual ist " << bin;

}


Dualrechnung::~Dualrechnung(){}

c_test.cpp:

#include "c.cpp"
#include <iostream>


int main(){

    Dualrechnung *d = new Dualrechnung();
    delete d;
    return 0;
}

Upvotes: 0

Views: 2691

Answers (2)

Slava
Slava

Reputation: 44238

If I understood you correctly you need to convert int to set of bits and vice versa. Just use std::bitset which has constructor from unsigned long and method to convert it back (you can also convert it to/from string of 0 and 1s).

Upvotes: 2

mariusz_latarnik01
mariusz_latarnik01

Reputation: 659

I wrote smth like this for you:

#include <iostream>
#include <vector>

using namespace std;

int main() {
    vector<int> myNumInVect = {1, 1, 0, 0, 1};
    int myNumInInteger = 0;
    int baseOfMyNumInVector = 2;
    for (int i : myNumInVect) {
        myNumInInteger = myNumInInteger * baseOfMyNumInVector + i;
    }
    cout << myNumInInteger;
    return 0;
}

(output of this code is 25 as expected (11001(2)=25(10))

it uses Horner's method, so number of operation '*' = vector.size(). It's easy adaptable to others bases positional numeral systems vector (by changing the baseOfMyNumInVector).

-----------@edit-----------

I know you have it, but i want also to show you how easy can be done conversion dec2givenBase without any pow, or smth like this:

#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;

int main() {
    int myNumInInteger = 111;
    int baseOfMyNumInVector = 2;
    vector<int> myNumInVect;

    while (myNumInInteger > 0) { // using Horner Scheme for switching base
        myNumInVect.push_back(myNumInInteger % baseOfMyNumInVector);
        myNumInInteger /= baseOfMyNumInVector;
    }

    std::reverse(myNumInVect.begin(), myNumInVect.end()); // reverse (bcs there is no push_front() method in vector)

    if (myNumInVect.empty()) { // handling the 0 case
        myNumInVect.push_back(0);
    }

    for (auto digit : myNumInVect) { // write the result
        cout << digit;
    }
    return 0;
}

Upvotes: 1

Related Questions