/*

Copyright: 1999, All rights reserved.
Program: stdlib
Version: 3.1
Created: 9/26/99
Revised: 10/20/99
File: stdlib.cpp
Programmer: C. S. Tritt, Ph.D.
Course: CS-150
Assignment: Example
Compiler: Microsoft Visual C++ 6.0
Target: Win32

Description:

   This program tests functions that should be declared in the <stdlib.h> and
   <cstdlib> files.  It also tests the assert mechanism for error handling and 
   demonstrates the use of command line arguments.  It contains a mix of C/C++
   and some low level code due to the use of some old C style features.

Revisions:

  There have been no major revisions of this program.

Constants and Variables:

  See code for constant and variable descriptions.

*/

#define DEBUG // NDEBUG disables assert().

// Included files.


#include <cstdlib> // Required for srand(), rand() & system().
#include <iostream> // Required for stream output.
#include <iomanip> // Required for "endl."
#include <ctime> // Required for time().
#include <cassert> // Required for assert().
#include <string> // Required for char* to C++ string conversion and output.

using namespace std;

int main(int argc, char *argv[])
{

// Display command line arguments.   
   
   int i;
   for(i = 0; i < argc; i++) // Loop through argument array.
   {
      string arg = argv[i]; // Convert C "string" to C++ string.
      cout << "Argument " << i << " is "<< arg << endl;
   }

// Get the current time in seconds since midnight 1/1/70.

   time_t when; // A time_t argument is required by time.
   int now = time(&when); // Now is current time.  When is not used.
   cout << "The returned time was " << now << endl;

// Seed random number generator with mod time and get two random numbers. 

/*
   The MSVC++ 6.0 random number genertor does not seem to be particularly
   good so I'll beef it up a bit by burning some calls to it.
*/

   srand(now);
   int count = rand() % 73;
   for (i = 0; i < count; i++) rand();
   int r1 = rand();
   count = rand() % 67;
   for (i = 0; i < count; i++) rand();
   int r2 = rand();

   cout << "Random numbers should be between 0 and " << RAND_MAX << endl;
   cout << "Random numbers are: " << r1 << " and " << r2 << endl;

// Tell user if NDEBUG is defined and do assert.

   #if defined(NDEBUG)
      cout << "NDEBUG defined.  Assert disabled,\n";
   #else
      cout << "NDEBUG not defined.  Assert enabled.\n";
   #endif

   cout << "About to assert(r1 < r2)\n";
   assert(r1 < r2);
   cout << "Assertion must have been true or disabled.\n";

// Perform a system call.

   cout << "Now try a system call (in this case \"dir\").\n";
   system("dir");

// Everything worked, but exit(0) causes a warning.

   return 0;
}