Need some help or advice in C++ program

I need just a little help with my program,program rans and it will display 10 different lotto numbers. However i raninto a problem, everytime i run it i get numbers that are the same in the draw. Can anyone give me some advice or help on how i can prevent that from happening. Can i do FOR statement to reset all to 0 or set array to 0? how would i go doing that? I included the program below. Thanks for the help

Code:

---

//sp
//11/30/04

#include <iostream>

using namespace std;

#include <iomanip>


using std::setw;


#include <cstdlib>
#include <ctime>

int main()
{
      const int size = 6;
      int a[size] = {0,0,0,0,0,0};
      srand(time(0));


      for(int w=1; w<11;w++){
          cout <<"For game #"<< setw(3) << w << "=";

          for(int i=0;i<size;i++){
              a[i] = rand()%59 + 1;
              cout << setw(5) << a[i] <<"  ";
                    }
          cout <<endl;
                }
            cout <<endl;
            return 0;
}

---

I'm afraid I don't understand your problem. The program works fine and gives seemingly random numbers. Can you give an example of what you're getting as well as an example of what you want to get?

Are you referring to the program giving you 10 random numbers at first, but then giving you those same numbers each time you run the program?

>then giving you those same numbers each time you run the program?
If this is the case then srand isn't doing it's job on the OP's implementation. Which is entirely possible since using time directly to seed srand is non-portable. However, clarification would be a good idea before we start throwing out ideas. ;)

the problem is that i get the following output:

For game # 1= 42 36 37 51 57 57 <-------------- There are two 57's, there cant be 2 same numbers in a draw for lotto.
For game # 2= 21 35 20 20 44 14
For game # 3= 5 8 2 31 59 12
For game # 4= 45 9 33 10 23 38
For game # 5= 25 12 30 2 50 12
For game # 6= 54 43 8 34 54 21
For game # 7= 10 23 43 18 48 52
For game # 8= 30 47 37 23 12 5
For game # 9= 42 29 58 47 56 47
For game # 10= 5 28 13 43 47 38

You'll need a function to check for duplicate, then. While it's true, keep re-generate a new random number.
Just go through previously generated random number. Not the fastest algorithm, but fast enough for small count of random number.

Try this:

Code:

---


//sp
//11/30/04

#include <iostream>

using namespace std;

#include <iomanip>


using std::setw;


#include <cstdlib>
#include <ctime>

int main()
{
      const int size = 6;
      int a[size] = {0,0,0,0,0,0};
      int tmp, j;
      j = 0;
      srand(time(0));


      for(int w=1; w<11;w++){
          cout <<"For game #"<< setw(3) << w << "=";

          for(int i=0;i<size;i++){
              tmp = rand()%59 +1;
              while(j < size) {
                if(a[j] == tmp) {        // if number has already been taken
                    tmp = rand()%59 + 1;  // generate new rand
                    j=0;
                }
                else {
                    j++;
                }
              }
              a[i] = tmp;
              cout << setw(5) << a[i] <<"  ";
                    }
          cout <<endl;
                }
            cout <<endl;
            return 0;
}

---

Note the inner while loop inside your nested for loop. This loop will check the current contents of your array for a duplicate number - if the number has already been called, the loop will reset and generate a new rand to try again.

I didn't compile this, but it should work just fine. If anything, you should get the general idea. Hope this helps.

>there cant be 2 same numbers in a draw for lotto.
Make sure there aren't any duplicates then. You could do it with loops and such, but that's not very efficient. A better way is to take a random sample of a list of valid draws:

Code:

---

#include <algorithm>
#include <cstdlib>
#include <ctime>
#include <iostream>
#include <iterator>

using namespace std;

void random_draw(int a[], int size)
{
  int list[59];

  for (int i = 0; i < 59; i++)
    list[i] = i + 1;

  for (int i = 0; i < size; i++) {
    int r = rand() % (59 - i) + 1;
    a[i] = list[i + r];
  }
}

int main()
{
  int a[5];

  for (int i = 1; i <= 5; i++) {
    random_draw(a, 5);
    cout<<"Game #"<< i <<": ";
    copy(a, a + 5, ostream_iterator<int>(cout, " "));
    cout<<endl;
  }
}

---

thanks alot for all the help, the program still gives me double number, but i do get the general idea of it and thats all i need i will play around with it and try to get it to work.


thank you!!!

>the program still gives me double number
Which solution did you use?

thanks to all of your help specially neolyn i used his but i had to add 1 line of code.

at the end of code i added j=0; since it reseted it in loop but not out of it.

so the program looks like this now

Code:

---

//sp
//11/30/04

#include <iostream>

using namespace std;

#include <iomanip>


using std::setw;


#include <cstdlib>
#include <ctime>

int main()
{
      const int size = 6;
      int a[size] = {0,0,0,0,0,0};
      int tmp, j;
      j = 0;
      srand(time(0));


      for(int w=1; w<11;w++){
          cout <<"For game #"<< setw(3) << w << "=";

          for(int i=0;i<size;i++){
              tmp = rand()%59 +1;
              while(j < size) {
                if(a[j] == tmp) {        // if number has already been taken
                    tmp = rand()%59 + 1;  // generate new rand
                    j=0;
                }
                else {
                    j++;
                }
              }
              a[i] = tmp;
                j = 0;          // added this line to the program
              cout << setw(5) << a[i] <<"  ";
                    }
          cout <<endl;
                }
            cout <<endl;
            return 0;
}

---