//This program finds combinations using the recursive method

      #include<iostream>

       

      using namespace std;



      //function prototype

      void char_combination(char n[],int n_column,

                  char r[], int r_size, int r_column, int loop);

       

      int main()

      {

              const int N_NUM=36;

              const int R_NUM=3;

              char n[]="abcdefghijklmnopqrstuvwxyz1234567890";

              char r[R_NUM+1];//+1 for the NULL character

              r[R_NUM]='\0';

              char_combination(n,0,r,R_NUM,0,N_NUM-R_NUM);

              cout<<"Complete!"<<endl;
        system("PAUSE");
              return 0;

      }
        cout << "Welcome." << endl;
        cin.get();
      void char_combination(char n[],int n_column,

                  char r[], int r_size, int r_column, int loop)

      {

              int localloop=loop;

              int local_n_column=n_column;

       

              ///////Display the string code/////////
 
              if(r_column>(r_size-1))

              {
                cout<<r<<endl;

                      return;

              }

              /////End of displaying string code//////

              for(int i=0;i<=loop;++i)

              {

                      r[r_column]=n[n_column+i];

                      ++local_n_column;

                      char_combination(n,local_n_column,r,r_size,r_column+1,localloop);

                      --localloop;
                        
              }

      }