#include <iostream>
#include <cassert>

using namespace std;

const char* BINARY_DIGITS = "01";

void int2bin(int n, char* txt);

int main() {
    char txt[64];
    while (true) {
        int n;
        cout << "Enter an integer number (q for the end):" << endl;
        if (!(cin >> n))
            break;
        int2bin(n, txt);
        cout << "Binary representation: " << txt << endl;
    }
    return 0;
}

void int2bin(int n, char* txt) {
    if (n == 0) {
        txt[0] = '0'; txt[1] = 0;
        return;
    }

    char* pos = txt;
    if (n < 0) {
        *pos = '-';
        ++pos;
        n = (-n);
    }
    char* beg = pos;

    assert(n > 0);
    while (n != 0) {
        int r = n%2;
        assert(0 <= r && r < 2);
        *pos = BINARY_DIGITS[r];
        ++pos;
        n /= 2;
    }
    *pos = 0;   // Terminate the text string

    // Invert the text
    --pos;
    while (beg < pos) {
        // Swap two digits
        char tmp = *beg;
        *beg = *pos; *pos = tmp;
        ++beg; --pos;
    }
}