subset.c

/*This code print all the subset of a given set*/


#include<stdio.h>
#include<math.h>
#include<malloc.h>
//#define ARRAYSIZE(x) sizeof(x)/sizeof(x[0])
int main()
{
    int *set;
    int arraysize,i,j,count;
    printf("Enter number of elements in array: ");
    scanf("%d",&arraysize);

    set = calloc(arraysize, sizeof(int));
    /*filling the array elements by users*/
    printf("\nNow enter all the elements which must be unique: \n");
    for(i=0;i<arraysize;i++)
        {
            printf("Enter element %d: ",i+1);
            scanf("%d",&set[i]);
        }
    for(i=0;i<pow(2,arraysize);i++)
        {   count=0;
            printf(" ( ");
            for(j=0;j<arraysize;j++)
    /*if array has 'n' elements then check all 'n' bits of i (from 0 to n-1) either it is set or not*/
    /*if jth bit of i is set then array[j] will be printed as subset*/
                if((1<<j) & i)
                    {   /*if there is more than 1 element in a subset then put ',' in between them*/
                        if(count>0)
                            printf(",");
                        count++;

                         printf("%d",set[j]);
                    }
                  printf(" ),");
        }printf("\b ");


free(set);
return 0;
}//main