How to generate random number in C++?

#include <iostream> 
#include <ctime> 
#include <cstdlib> 

using namespace std; 

int generate_random_number( int uLowest, int uHighest, bool bSeed )
{
	// Seed the random number generated if requried.
	if ( true == bSeed )
	{
		srand((unsigned)time(0));
	}

	// Create a range value between which a number will be generated.
	int nRange = (uHighest-uLowest) + 1;
	
	// Generate the random number.
	int nRandomInteger = uLowest + int( nRange * rand() / (RAND_MAX + 1.0) ); 
	
	return nRandomInteger;
}

int main() 
{ 
	cout << generate_random_number( 1, 1000, true ) << endl;
	cout << generate_random_number( 1, 1000, false ) << endl;
	cout << generate_random_number( 1, 1000, false ) << endl;
	cout << generate_random_number( 1, 1000, false ) << endl;

	return 0;
	
}

#include <iostream>
#include <ctime>
using namespace std;


int main(){
    
  int rannum;          // define variables
  bool found = 1;
  long sec;
  
  time( &sec);      // use time function to get number of seconds from 1/1/1970
  
  srand((unsigned)sec); // use this number to seed the srand() function
  
  while (found == 1){         // use loop to look for desired number
        rannum = rand();
        if ( rannum >= 0 && rannum <= 15){  // turn off the loop when number is found
            found = 0;}
            }
        cout << rannum; // display the number
        cin.get();
}

int seed, rannum;
cin >> seed;
cin.ignore();
srand (seed);
rannum = rand();
cout << rannum;
cin.get();

long sec;
time( &sec);
srand ( (unsigned)sec);