A simple program to illustrate bitwise masking and merging to determine if a string contains duplicates.

finding_duplicates_in_string_using_bitwise_ops.cpp

// Simple program to illustrate bitwise ops to check string for duplicates
#include <iostream>
using namespace std;


int main()
{
  char * A = new char[20];
  cout << "Enter string to be checked for duplicates" << endl;
  cin >> A;
  long int H=0, x=0;
  int i;

  for(i=0; A[i] != '\0'; i++)
  {
    x = 1;
    x = x << (A[i] - 97);
    if((x&H) > 0) // masking - checking if bit is on/off
      cout << A[i] << " is a duplicate" << endl;
    else
      H = x | H; // merging - setting bit
  }

  delete [] A;

  return 0;
}