C++ program to print all subsets or all combinations of elements of a set

Here are C++ programs to print all subsets or all combinations of elements in a set. First program print all subset of a set using for-loop, second program uses bitwise operator to print all subsets and program uses recursion.

Method 1 : C++ programs to print all subsets or all combinations of elements in a set using for-loop

#include<iostream>
#include<math.h>
using namespace std;
int main()
{
    int a[20],n,tsets,d,rem;
    cout<<"Enter how many elements in set ";
    cin>>n;
    cout<<"Enter elements ";
    for(int i=0;i<n;i++)
        cin>>a[i];
    tsets=pow(2,n);
    for(int i=0;i<tsets;i++)
    {
        cout<<endl<<"(";
        d=i;
        for(int j=0;d>0;j++)
        {
            rem=d%2;
            d/=2;
            if(rem>0)
                cout<<" "<<a[j]<<" ";
        }
        cout<<")";
    }
    return 0;
}

Method 2 : C++ programs to print all subsets or all combinations of elements in a set using bitwise operator

#include<iostream>
#include<math.h>
using namespace std;
int main()
{
    int a[20],n,tsets;
    cout<<"Enter how many elements in set ";
    cin>>n;
    cout<<"Enter elements ";
    for(int i=0;i<n;i++)
        cin>>a[i];
    tsets=pow(2,n);
    for(int i=0;i<tsets;i++)
    {
        cout<<endl<<"(";
        for(int j=0;j<n;j++)
        {
            if(i&(1<<j))
                cout<<" "<<a[j]<<" ";
        }
        cout<<")";
    }
    return 0;
}

Method 3 : C++ programs to print all subsets or all combinations of elements in a set using recursion

#include<iostream>
#include<math.h>
using namespace std;
void print(int (&a)[10],int i,int j)
{
    if(j<0)
        return;
    if(i&(1<<j))
        cout<<a[j]<<" ";
    print(a,i,j-1);
}
void set(int (&a)[10],int i,int n)
{
    if(i==0)
        return ;
    print(a,i,n);
    cout<<endl;
    set(a,i-1,n);
}
int main()
{
    int n,result,a[10];
    cout<<"How many numbers to be entered : ";
    cin>>n;
    cout<<"Enter numbers ";
    for(int i=0;i<n;i++)
        cin>>a[i];
    cout<<"Subsets : "<<endl;
    set(a,pow(2,n)-1,n);
    return 0;
}

OUTPUT