// CSCI 2720			Data Structures			     Spring 2004

// randdemo.cc
// demonstrate srand( ) and rand( ) library functions

#include <iostream>
using namespace std;

int main(int argc, char* argv[]){  // argc and argv[] allow main( )
                                   // to read command line arguments 

  cout << "This is the output from program " << argv[0] << endl;
	 // above, argv[0] is the command, i.e., the name of the executable 

  if (argc < 2 )  // case of no second argument 
    srand(0);     // default value of "seed" is set to 0
  else
    srand( atoi( argv[1]));  // second argument converted from string 
			     // (alphabetic) to integer, then used as seed

  for (int i = 0; i < 20; i++)       // 20 numbers are to be generated; 
    cout << rand( ) << endl;         // the output of rand( ) is a 16 bit
                                     // integer >= 0.

  return 0;
}

// Note that the seed was only set once, by the call to srand( ).
// Subsequently, calls to rand( ) produced a sequence of "random"
// numbers.  Actually they are pseudo-random.  You can generate
// exactly the same sequence later by setting the seed to the same
// value.  Normally you won't want to do that unless you need to
// compare two different algorithms on exactly the same input
// data or sequence of operations.