string subsequence

#include <bits/stdc++.h>
using namespace std;

// str : Stores input string
// n : Length of str.
// curr : Stores current permutation
// index : Index in current permutation, curr
void printSubSeqRec(string str, int n,
           int index = -1, string curr = "")
{
    // base case
    if (index == n)
        return;

    cout << curr << "\n";
    for (int i = index + 1; i < n; i++) {

        curr += str[i];
        printSubSeqRec(str, n, i, curr);

        // backtracking
        curr = curr.erase(curr.size() - 1);
    }
    return;
}

// Generates power set in lexicographic
// order.
void printSubSeq(string str)
{
    printSubSeqRec(str, str.size());
}

// Driver code
int main()
{
    string str = "cab";
    printSubSeq(str);
    return 0;
}