Stopping same number from appearing twice?

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Re: Stopping same number from appearing twice?

 
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  #11
Jun 21st, 2008
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Originally Posted by salman213 View Post
would this be better or worse ???

C++ Syntax (Toggle Plain Text) 
  1. #include <iostream>
  2.  
  3. using namespace std;
  4.  
  5. int check (unsigned int checkvariable[]);
  6.  
  7. int main()
  8. {
  9.     srand(time(NULL));
  10.  
  11.     unsigned int lotteryBall[9];
  12.  
  13.     for(int i = 0; i <=7; ++i)
  14. {
  15.             lotteryBall[i] = rand() % 48 + 1;
  16.  
  17.             cout << lotteryBall[i] << " ";
  18.  
  19.             if(i == 7)
  20.   {
  21.         do {
  22.             lotteryBall[i+1] = rand() % 48 + 1; 
  23.             }while (check(lotteryBall));
  24.   cout << "*" << lotteryBall[i+1] << "*"; 
  25.   }
  26.  
  27.  }
  28.  
  29.     cin.get();
  30.  
  31.     return 0;
  32. }
  33.  
  34. int check (  unsigned int checkvariable[])
  35. {
  36.     for(int a=0;a<=7;++a)
  37.     {
  38.             if (checkvariable[a]==checkvariable[8])
  39.             {return true;
  40.              break;}
  41.              else if (a==7)
  42.              return false;
  43.     }
  44.  
  45. }

You have some strange formatting here. If you line things up, it'll be easier to read. I changed lines 13 and 20 from 48 to 10 to drastically increase the odds of getting repeats and I got them. You want to call your check function each time you generate a new random number (not necessary the first time), not just for the last ball. Also, you have a function that returns an integer returning true and false. While that's not an error, you should probably have the function return a boolean value.

C++ Syntax (Toggle Plain Text) 
  1. #include <iostream>
  2. using namespace std;
  3.  
  4. int check (unsigned int checkvariable[]);
  5.  
  6. int main()
  7. {
  8.     srand(time(NULL));    
  9.     unsigned int lotteryBall[9];
  10.  
  11.     for(int i = 0; i <=7; ++i)
  12.     {
  13.         lotteryBall[i] = rand() % 10 + 1;  
  14.         cout << lotteryBall[i] << " ";
  15.  
  16.         if(i == 7)
  17.         {
  18.             do 
  19.             {
  20.                 lotteryBall[i+1] = rand() % 10 + 1; 
  21.             }
  22.             while (check(lotteryBall));
  23.  
  24.             cout << "*" << lotteryBall[i+1] << "*"; 
  25.         }
  26.     }
  27.  
  28.     cin.get();    
  29.     return 0;
  30. }
  31.  
  32. int check (  unsigned int checkvariable[])
  33. {
  34.     for(int a=0;a<=7;++a)
  35.     {
  36.             if (checkvariable[a]==checkvariable[8])
  37.             {
  38.                 return true;
  39.                 break;
  40.             }
  41.             else if (a==7)
  42.                 return false;
  43.     }    
  44. }
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Re: Stopping same number from appearing twice?

 
0
  #12
Jun 21st, 2008
GOOD POINT, never noticed that.

so how about this

C++ Syntax (Toggle Plain Text) 
  1. #include <iostream>
  2. using namespace std;
  3. bool check (unsigned int checkvariable[], int a);
  4. int main()
  5. {
  6.     srand(time(NULL));
  7.     unsigned int lotteryBall[9];
  8.     for(int i = 0; i <=8; ++i)
  9. {
  10.             do 
  11.             {
  12.                 lotteryBall[i] = rand() % 10 + 1;
  13.             }
  14.             while (check(lotteryBall, i));
  15.  
  16.             if(i == 8)
  17.                   cout << "*" << lotteryBall[i] << "*";
  18.             else 
  19.                   cout << lotteryBall[i] << " ";
  20.  
  21. }    
  22.     cin.get();  
  23.     return 0;
  24. }
  25.  
  26. bool check (unsigned int checkvariable[], int a)
  27. {
  28.     for(int b=0;b<=a;b++)
  29.     {
  30.             if (a==b)
  31.             {
  32.             return false;
  33.             break;
  34.             }
  35.             if(checkvariable[b]==checkvariable[a])
  36.             {
  37.             return true;
  38.             break;
  39.             }      
  40.     }
  41. }



ONE QUESTION: I THOUGHT I READ THAT IF YOU WANTED TO USE THE SRAND() FUNCTION YOU MUST INCLUDE THE DIRECTIVE: ctime. In this case I did not and it still works??
Last edited by salman213; Jun 21st, 2008 at 6:24 pm.
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Re: Stopping same number from appearing twice?

 
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  #13
Jun 21st, 2008
wouldn't something like this be better? I mean if c++ gives the find function why not use it?

#include <iostream>
using namespace::std;

int main()
{
	srand(time(NULL));
	unsigned int lotteryBall[7];
	unsigned int tempBall;
	unsigned int* search;
	for(int i=0;i<7;i++)
	{
		tempBall=rand() % 10 + 1;
		search= find(lotteryBall, lotteryBall+7,tempBall);
		if(search==lotteryBall+7)
		{
		//number is not found
		lotteryBall[i]=tempBall;
		cout<< lotteryBall[i]<<' ';
		}
		else{i--;}
	}
	cin.get();
	return 0;
}

about ctime I am not sure but I do not include it and it works as well(at least with g++ on linux).
Last edited by kaleshwar; Jun 21st, 2008 at 7:46 pm. Reason: code tags
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Re: Stopping same number from appearing twice?

 
0
  #14
Jun 21st, 2008
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Originally Posted by salman213 View Post
GOOD POINT, never noticed that.

so how about this

C++ Syntax (Toggle Plain Text) 
  1. #include <iostream>
  2. using namespace std;
  3. bool check (unsigned int checkvariable[], int a);
  4. int main()
  5. {
  6.     srand(time(NULL));
  7.     unsigned int lotteryBall[9];
  8.     for(int i = 0; i <=8; ++i)
  9. {
  10.             do 
  11.             {
  12.                 lotteryBall[i] = rand() % 10 + 1;
  13.             }
  14.             while (check(lotteryBall, i));
  15.  
  16.             if(i == 8)
  17.                   cout << "*" << lotteryBall[i] << "*";
  18.             else 
  19.                   cout << lotteryBall[i] << " ";
  20.  
  21. }    
  22.     cin.get();  
  23.     return 0;
  24. }
  25.  
  26. bool check (unsigned int checkvariable[], int a)
  27. {
  28.     for(int b=0;b<=a;b++)
  29.     {
  30.             if (a==b)
  31.             {
  32.             return false;
  33.             break;
  34.             }
  35.             if(checkvariable[b]==checkvariable[a])
  36.             {
  37.             return true;
  38.             break;
  39.             }      
  40.     }
  41. }



ONE QUESTION: I THOUGHT I READ THAT IF YOU WANTED TO USE THE SRAND() FUNCTION YOU MUST INCLUDE THE DIRECTIVE: ctime. In this case I did not and it still works??
Yeah, that program works well. srand is from cstdlib, not ctime. NULL is in ctime and cstdlib. I don't know why it works without cstdlib, but it does. Still, probably best to #include it anyway to be safe. If you don't #include iostream and add using namespace std , you seem to run into problems with this program regarding srand. Not sure why.
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Re: Stopping same number from appearing twice?

 
0
  #15
Jun 21st, 2008
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Originally Posted by kaleshwar View Post
wouldn't something like this be better? I mean if c++ gives the find function why not use it?

#include <iostream>
using namespace::std;

int main()
{
	srand(time(NULL));
	unsigned int lotteryBall[7];
	unsigned int tempBall;
	unsigned int* search;
	for(int i=0;i<7;i++)
	{
		tempBall=rand() % 10 + 1;
		search= find(lotteryBall, lotteryBall+7,tempBall);
		if(search==lotteryBall+7)
		{
		//number is not found
		lotteryBall[i]=tempBall;
		cout<< lotteryBall[i]<<' ';
		}
		else{i--;}
	}
	cin.get();
	return 0;
}

about ctime I am not sure but I do not include it and it works as well(at least with g++ on linux).
This program gave good results too.
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