sample-random-variable.cc

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/*
 * SPDX-License-Identifier: GPL-2.0-only
 */
#include "ns3/command-line.h"
#include "ns3/nstime.h"
#include "ns3/random-variable-stream.h"
#include "ns3/simulator.h"
 
#include <iostream>
 
/**
 * \file
 * \ingroup core-examples
 * \ingroup randomvariable
 * Example program illustrating use of ns3::RandomVariable
 */
 
using namespace ns3;
 
/**
 * This program can be run from ns3 such as
 * `./ns3 run sample-random-variable`
 *
 * This program is about as simple as possible to display the use of ns-3
 * to generate random numbers.  By default, the uniform random variate that
 * will be outputted is 0.816532.  Because ns-3 uses a fixed seed for the
 * pseudo-random number generator, this program should always output the
 * same number.  Likewise, ns-3 simulations using random variables will
 * behave deterministically unless the user changes the Run number or the
 * Seed.
 *
 * There are three primary mechanisms to change the seed or run numbers
 * from their default integer value of 1:
 *
 * 1. Through explicit call of SeedManager::SetSeed () and
 *    SeedManager::SetRun () (commented out below)
 * 2. Through the passing of command line arguments such as:
 *    ./ns3 run program-name --command-template="%s --RngRun=<value>"`
 * 3. Through the use of the NS_GLOBAL_VALUE environment variable, such as:
 *    `$ NS_GLOBAL_VALUE="RngRun=<value>" ./ns3 run program-name`
 *
 * For instance, setting the run number to 3 will change the program output to
 * 0.775417
 *
 * Consult the ns-3 manual for more information about the use of the
 * random number generator
 */
 
int
main(int argc, char* argv[])
{
    CommandLine cmd(__FILE__);
    cmd.Parse(argc, argv);
 
    // SeedManager::SetRun (3);
 
    Ptr<UniformRandomVariable> uv = CreateObject<UniformRandomVariable>();
 
    std::cout << uv->GetValue() << std::endl;
 
    return 0;
}