q17.1.cpp

#include <iostream>

using namespace std;

int shiftbits(int num, int count, bool dir) {
  if (dir) {
    for (int it = 0; it < count; it++) {
      num = num >> 1;
    }
  }

  else {
    for (int it = 0; it < count; it++) {
      num = num << 1;
    }
  }

  return num;
}

int sum_helper(int a, int b, bool carry) {
  int sum = 0;
  int count = 0;
  int f = 0;
  bool b1, b2;
  while ((a != 0) && (b != 0)) {
    b1 = (a & 0x01);
    b2 = (b & 0x01);
    f = b1 ^ b2 ^ carry;
    sum |= shiftbits(f, count, 0);
    carry = (b1 & b2) | ((b1 | b2) & carry);
    a = shiftbits(a, 1, 1);
    b = shiftbits(b, 1, 1);
    count++;
  }

  return sum;
}

int sum(int a, int b) {
  // int sum = 0;
  // int sign_a = a < 0 ? -1 : 1;
  // int sign_b = b < 0 ? -1 : 1;

  return sum_helper(a, b, 0);
}

// int add ( int a, int b) {
//  while (b != 0) {
//  int sum = a ^ b;
//  int carry = (a & b) << 1;
//  a = sum;
//  b = carry;
//  cout << a << ", " << b << endl;
//  }
//  return a;
// }

int main([[maybe_unused]] int argc, [[maybe_unused]] char **argv) {

  int a = 29, b = 14;

  int ans = sum(a, b);
  cout << " sum of " << a << " and " << b << " : " << ans;
  return 0;
}