Random.cpp

Go to the documentation of this file.

/*
 * Random.cpp
 *
 * Copyright (C) 2011 IBR, TU Braunschweig
 *
 * Written-by: Johannes Morgenroth <morgenroth@ibr.cs.tu-bs.de>
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 */

#include "Random.h"
#include <time.h>
#include <stdlib.h>
#include <vector>
#include <sys/time.h>

namespace dtn
{
        namespace utils
        {
                Random::Random()
                {
                        static bool initialized = false;

                        if (!initialized) {
                                struct timeval time;
                                ::gettimeofday(&time, NULL);

                                // initialize a random seed only once
                                srand(static_cast<unsigned int>((time.tv_sec * 100) + (time.tv_usec / 100)));
                                initialized = true;
                        }
                }

                Random::~Random()
                {
                }

                const std::string Random::gen_chars(const dtn::data::Length &size) const
                {
                        static const char text[] = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
                        std::vector<char> dst(size);
                        const dtn::data::Length len = size - 1;
                        for ( dtn::data::Length i = 0; i <= len; ++i )
                        {
                                dst[i] = text[rand() % (sizeof text - 1)];
                        }
                        return std::string(dst.begin(), dst.end());
                }
        }
}