Converting from decimal to binary in the right order

Question

i'm a complete noob in c++ and we had to do a programm in school that calculates the cross sum of a number and then convert this number to a binary number.

The problem I have now is that the binary number is in reverse order. I want to add the digits into an array and then cout the array from right to left, but I do not have any Idea how to do it. :/

Could someone explain / show me how to do it?

And I am using the do while loops because that was the requirement for the task...

int main()
{
    int digit, sum = 0, rem;

    cout<<"Enter a positive digit" << endl;
    cin >>  digit;

    do {
        sum= sum + (digit%10); 
        digit /= 10;
    }
    while (digit!= 0);

    cout <<"Cross sum" << sum << endl; 

    do {
        rem = sum % 2;
        sum /= 2;
        cout << "Decimal in Binary: " << rem << endl;
    }
    while(sum>0);

    return 0;
}

https://stackoverflow.com/questions/19275955/convert-little-endian-to-big-endian/19276193 — agent_bean, Sep 27 '19 at 10:05
`digit` is already binary. There is no decimal here. Any decimal to binary conversion is already carried out by `cin >> digit;`. — user207421, Sep 27 '19 at 10:10
@user207421 Given a `sum` of 6, the OP wants an output of "110", but is getting "011" - that is what he means by "binary". — Martin Bonner supports Monica, Sep 27 '19 at 10:54
Also you print the binary number on the wrong order. One way to do it is to use code start's recursive suggestion below. — Jonas Byström, Sep 27 '19 at 10:55
@JonasByström - What do you mean "**also** you print the binary number [in] the wrong order"? The fact the binary number is coming out in the wrong order is the *whole point* of the OP's question. — Martin Bonner supports Monica, Sep 27 '19 at 10:57
@MartinBonner: also, as in apart from the unnecessary "decimal conversion" talked about above. — Jonas Byström, Sep 27 '19 at 11:32
OP: Start with pen and paper. "If this, than that..." and draw lines. it *will* help. Randomlly throwing in programming stuff doesn't help. Figure out the logic flow **you** want. — Ted Lyngmo, Sep 28 '19 at 00:11

score 0 · Answer 1 · edited Sep 27 '19 at 10:55

0

This function will print decimal to binary in right order:

void decToBin(int n) {
    if (n == 0) {
        return;
    }
    decToBin(n / 2);
    cout << n % 2;
}

edited Sep 27 '19 at 10:55

Martin Bonner supports Monica

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answered Sep 27 '19 at 10:10

code start

1
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You may want to use right shift `operator>>` and the binary AND `operator &`. Many times more efficient than remainder and division (however compiles may recognize the pattern and make the optimization). – Thomas Matthews Sep 27 '19 at 16:30

Converting from decimal to binary in the right order

1 Answers1