Question

Is this program OK, or can it be improved (but simply)? How do I make sure no repeat numbers are entered?

int n;
int array[9];

cout<<"Enter Number Between 9-0 Only"<<endl;
for(int i = 0; i<=10; i++){
    cout<<"Enter Number" <<(i+1)<<endl;
    cin >> n;
    if((n >= 0) && (n <=9)){
       array[i]=n;
     }
        else{
        cout<<"Numbers from 0-9 only\n"<<endl;

        break;
    }

}

Answer 1

(edit) complete, compiling code

To check if the numbers are used with higher performance, try something like this (using the working code from Jack Radcliffe):

#include <iostream>
using namespace std;

int main()
{
  int n = 0;
  int array[9] = {0};

  bool isUsed[10] = {0};

  for(int i = 0; i < 9; i++) 
  {
    cout << "Enter Number " << (i + 1) << endl;
    cin >> n;

    if((n >= 0) && (n <= 9))
    {
      if (isUsed[n] == false)
      {
        array[i] = n;
        isUsed[n] = true;
      }

      else
      {
        cout << "Number has already been used." << endl;
        i--;
      }
    }

    else 
    {
      cout << "Numbers from 0-9 only." << endl;
      i--;
    }
  }

  return 0;
}

Optimization isn’t exactly necessary with this simple of code, but it’s this seems to be an exercise of practice, so why not practice optimized code, too?