c++ random

                                    #include <cstdlib>
#include <iostream>
#include <ctime>
 
int main() 
{
    std::srand(std::time(nullptr)); // use current time as seed for random generator
    int random_variable = std::rand();
    std::cout << "Random value on [0 " << RAND_MAX << "]: " 
              << random_variable << '\n';
}

                                    #include <iostream>
#include <stdlib.h>
#include <time.h>
using namespace std;
int main() {
	srand(time(NULL)	);
	const char arrayNum[7] = {'0', '1', '2', '3', '4', '5', '6'};
	int RandIndex = rand() % 7;
	cout<<RandIndex<<endl;
	return 0;
}

                                    v1 = rand() % 100;         // v1 in the range 0 to 99
v2 = rand() % 100 + 1;     // v2 in the range 1 to 100
v3 = rand() % 30 + 1985;   // v3 in the range 1985-2014 

                                    #include <iostream>
#include <stdlib.h>     
#include <time.h> 
using namespace std;

int main()
{
	int num;
	srand(time(0));
		num = rand() % 10 + 1;
		cout << num << endl;
}

                                    /* rand example: guess the number */
#include <stdio.h>      /* printf, scanf, puts, NULL */
#include <stdlib.h>     /* srand, rand */
#include <time.h>       /* time */

int main ()
{
  int iSecret, iGuess;

  /* initialize random seed: */
  srand (time(NULL));

  /* generate secret number between 1 and 10: */
  iSecret = rand() % 10 + 1;

  do {
    printf ("Guess the number (1 to 10): ");
    scanf ("%d",&iGuess);
    if (iSecret<iGuess) puts ("The secret number is lower");
    else if (iSecret>iGuess) puts ("The secret number is higher");
  } while (iSecret!=iGuess);

  puts ("Congratulations!");
  return 0;
}