This prints out all possible combination of the given string.

combination.cc

// print all combinations of string
#include <iostream>
#include <vector>
using namespace std;

void combinations(const char str[]);
void combinations(const char str[], char buf[], bool used[], int bufpos, int cur, int len);
void combinations(const char str[], vector<char>& buf, int start, int len);

int main(int argc, char* argv[])
{
	if(argc!=2)
	{
		cerr << argv[0] << " [string]" <<endl;
		return -1;
	}

	combinations(argv[1]);
	return 0;
}

void combinations(const char str[], vector<char>& buf, int start, int len)
{
	for(int i=start; i<len; ++i)
	{
		buf.push_back(str[i]);
		//cout <<"bufsize: " << buf.size() << endl;
		for(size_t j=0; j<buf.size(); ++j)
			cout << buf[j];
		cout << endl;
		if( i < len)
			combinations(str, buf, i+1, len);
		buf.resize(buf.size()-1);
	}
}

void combinations(const char str[])
{
	int len = strlen(str);
	vector<char> buf;
	combinations(str, buf, 0, len);
	
}