Without repeating random numbers in C++

The need to generate random numbers without a recurrence . It may be useful for various things such as randomly ordered list items, forms random groups, shuffling cards, etc.. So algorithm would be something like:

1. Create an array and leave it empty.
2. Get a random number.
3. Check if that number exists in the array. If yes, return to step 2. If not, save the number in the matrix.

So the program is this:

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26

<cstdlib> # Include # include <ctime> <iostream> # include using namespace std ;   bool checkRep ( int n, int num [ ] ) { for ( int i = 0 ; i < 10 ; i + + ) if ( n == num [ i ] ) return true ; return false ; }   int main ( ) { srand ( time ( NULL ) ) ; int n, num [ 10 ] ; for ( int i = 0 ; i < 10 ; i + + ) { do n = 1 + rand ( ) % 10 , while ( checkRep ( n, num ) ) ; num [ i ] = n ; court << num [ i ] << "" ; } }

First of all, <cstdlib> is the correct way to include the library in c + + <stdlib.h>, same with <ctime>.

You see, we use a bool function ( which returns true or false ) to check if the random number already exists in our matrix. If any of the numbers is equal to our random number n , the function returns true , so that the cycle do-while since we call the function will be repeated again until the function returnsfalse .

When it gets out of do-while loop, we keep our n in place of the corresponding matrix, as shown on the screen and continue to the next position in the array.