C / C++ / MFC

int fac(int n)
{
  if (n == 0) return 1;
  else return n*fac(n - 1);    	    
}

void permute(char *string, int n, int rank)
{
  vector<char> vec;
  for (int ctr = 0; ctr < n; ctr++) vec.push_back(string[ctr]);

  for (int ctr = n; ctr >= 1; ctr--)
    {
      int quotient = rank/fac(ctr-1);
      char c = vec[quotient];
      vec.erase(vec.begin()+quotient);
      *string++ = c;
      rank%=fac(ctr-1);    	 
    }    		  
}

void showpermutes(char *string)
{
  char temp[20];  	
  int n = strlen(string);    	
  // if the string is too big, we can't continue
  if (n > 19) return;
  int nfac = fac(n);
  for (int ctr = 0; ctr < nfac; ctr++)
    {	         
      strcpy(temp, string);    	     
      permute(temp, n, ctr);    	     
      cout << temp << endl;
    }     		       
}

int _tmain(int argc, _TCHAR* argv[])
{
	showpermutes("AB");
	system("PAUSE");
	getche();
	return 0;
}

TechAvtar wrote:

What will happen to the memory allocated for "hello"? Will it be released at assignment of "world"?

void CString::AllocBeforeWrite(int nLen)
{
	if (GetData()->nRefs > 1 || nLen > GetData()->nAllocLength)
	{
               // This release will release all the memory allocated previously, so you wont face any memory leak.
		Release();
		AllocBuffer(nLen);
	}
	ASSERT(GetData()->nRefs <= 1);
}