我尝试着创造一款带有骰子的游戏，我需要在其中添加一些随机数字(游戏邦注:即模拟骰子的边缘)。我知道如何在1到6之间
#include <cstdlib>
#include <ctime>
#include <iostream>
using namespace std;
int main()
{
srand((unsigned)time(0));
int i;
i = (rand()%6)+1;
cout << i << "\n";
}
并不是很好地工作，因为当我运行程序几次，这是我得到的输出:
6
1
1
1
1
1
2
2
2
2
5
2
所以我想要一个每次生成不同随机数的命令，而不是连续5次生成相同的随机数。是否有这样的命令?
当前回答
为每个RUN文件随机
size_t randomGenerator(size_t min, size_t max) {
std::mt19937 rng;
rng.seed(std::random_device()());
//rng.seed(std::chrono::high_resolution_clock::now().time_since_epoch().count());
std::uniform_int_distribution<std::mt19937::result_type> dist(min, max);
return dist(rng);
}
其他回答
每次生成不同的随机数，而不是连续六次生成相同的随机数。
用例场景
我把“可预测性”的问题比作一袋六块纸，每个纸上写着一个从0到5的值。每当需要一个新的数值时，就会从袋子里抽出一张纸。如果袋子是空的，那么数字被放回袋子。
根据这个，我可以创建一个算法。
算法
一个包通常是一个集合。我选择了bool[](也称为布尔数组，位平面或位图)来扮演袋子的角色。
我选择bool[]的原因是，每一项的索引已经是每张纸的值。如果论文需要在它们上面写任何东西，那么我将使用Dictionary<string, bool>代替它。布尔值用于跟踪数字是否已经绘制。
一个名为RemainingNumberCount的计数器被初始化为5，当选择一个随机数时，计数器会向下计数。这样，我们就不必在每次想要画一个新数字时，都要计算还剩下多少张纸了。
为了选择下一个随机值，我使用for..循环来扫描索引包，并使用一个计数器来计数，当索引为false时，称为NumberOfMoves。
NumberOfMoves用于选择下一个可用号码。NumberOfMoves首先被设置为0到5之间的随机值，因为有0..我们可以通过袋子的5个可行步骤。在下一次迭代中，NumberOfMoves被设置为0到4之间的随机值，因为现在有0..我们可以用4步穿过袋子。在使用这些数字时，可用的数字会减少，因此我们使用rand() % (RemainingNumberCount + 1)来计算NumberOfMoves的下一个值。
当NumberOfMoves计数器为零时，for..循环应该如下所示:
将当前值设置为与..循环的索引。 将包中的所有数字设置为false。 停止for..循环。
Code
上述解决方案的代码如下:
(将以下三个块依次放入主.cpp文件中)
#include "stdafx.h"
#include <ctime>
#include <iostream>
#include <string>
class RandomBag {
public:
int Value = -1;
RandomBag() {
ResetBag();
}
void NextValue() {
int BagOfNumbersLength = sizeof(BagOfNumbers) / sizeof(*BagOfNumbers);
int NumberOfMoves = rand() % (RemainingNumberCount + 1);
for (int i = 0; i < BagOfNumbersLength; i++)
if (BagOfNumbers[i] == 0) {
NumberOfMoves--;
if (NumberOfMoves == -1)
{
Value = i;
BagOfNumbers[i] = 1;
break;
}
}
if (RemainingNumberCount == 0) {
RemainingNumberCount = 5;
ResetBag();
}
else
RemainingNumberCount--;
}
std::string ToString() {
return std::to_string(Value);
}
private:
bool BagOfNumbers[6];
int RemainingNumberCount;
int NumberOfMoves;
void ResetBag() {
RemainingNumberCount = 5;
NumberOfMoves = rand() % 6;
int BagOfNumbersLength = sizeof(BagOfNumbers) / sizeof(*BagOfNumbers);
for (int i = 0; i < BagOfNumbersLength; i++)
BagOfNumbers[i] = 0;
}
};
控制台类
我创建这个Console类是因为它可以很容易地重定向输出。
下面的代码中…
Console::WriteLine("The next value is " + randomBag.ToString());
.．.可以用……
std::cout << "The next value is " + randomBag.ToString() << std::endl;
.．.然后这个Console类可以根据需要删除。
class Console {
public:
static void WriteLine(std::string s) {
std::cout << s << std::endl;
}
};
主要方法
用法示例如下:
int main() {
srand((unsigned)time(0)); // Initialise random seed based on current time
RandomBag randomBag;
Console::WriteLine("First set of six...\n");
randomBag.NextValue();
Console::WriteLine("The next value is " + randomBag.ToString());
randomBag.NextValue();
Console::WriteLine("The next value is " + randomBag.ToString());
randomBag.NextValue();
Console::WriteLine("The next value is " + randomBag.ToString());
randomBag.NextValue();
Console::WriteLine("The next value is " + randomBag.ToString());
randomBag.NextValue();
Console::WriteLine("The next value is " + randomBag.ToString());
randomBag.NextValue();
Console::WriteLine("The next value is " + randomBag.ToString());
Console::WriteLine("\nSecond set of six...\n");
randomBag.NextValue();
Console::WriteLine("The next value is " + randomBag.ToString());
randomBag.NextValue();
Console::WriteLine("The next value is " + randomBag.ToString());
randomBag.NextValue();
Console::WriteLine("The next value is " + randomBag.ToString());
randomBag.NextValue();
Console::WriteLine("The next value is " + randomBag.ToString());
randomBag.NextValue();
Console::WriteLine("The next value is " + randomBag.ToString());
randomBag.NextValue();
Console::WriteLine("The next value is " + randomBag.ToString());
Console::WriteLine("\nThird set of six...\n");
randomBag.NextValue();
Console::WriteLine("The next value is " + randomBag.ToString());
randomBag.NextValue();
Console::WriteLine("The next value is " + randomBag.ToString());
randomBag.NextValue();
Console::WriteLine("The next value is " + randomBag.ToString());
randomBag.NextValue();
Console::WriteLine("The next value is " + randomBag.ToString());
randomBag.NextValue();
Console::WriteLine("The next value is " + randomBag.ToString());
randomBag.NextValue();
Console::WriteLine("The next value is " + randomBag.ToString());
Console::WriteLine("\nProcess complete.\n");
system("pause");
}
示例输出
当我运行程序时，我得到以下输出:
First set of six...
The next value is 2
The next value is 3
The next value is 4
The next value is 5
The next value is 0
The next value is 1
Second set of six...
The next value is 3
The next value is 4
The next value is 2
The next value is 0
The next value is 1
The next value is 5
Third set of six...
The next value is 4
The next value is 5
The next value is 2
The next value is 0
The next value is 3
The next value is 1
Process complete.
Press any key to continue . . .
关闭声明
该程序是使用Visual Studio 2017编写的，我选择使用. net 4.6.1使其成为Visual c++ Windows控制台应用程序项目。
我在这里没有做任何特别的事情，所以代码应该也适用于早期版本的Visual Studio。
如果你正在使用boost lib，你可以通过以下方式获得一个随机生成器:
#include <iostream>
#include <string>
// Used in randomization
#include <ctime>
#include <boost/random/mersenne_twister.hpp>
#include <boost/random/uniform_int_distribution.hpp>
#include <boost/random/variate_generator.hpp>
using namespace std;
using namespace boost;
int current_time_nanoseconds(){
struct timespec tm;
clock_gettime(CLOCK_REALTIME, &tm);
return tm.tv_nsec;
}
int main (int argc, char* argv[]) {
unsigned int dice_rolls = 12;
random::mt19937 rng(current_time_nanoseconds());
random::uniform_int_distribution<> six(1,6);
for(unsigned int i=0; i<dice_rolls; i++){
cout << six(rng) << endl;
}
}
函数current_time_nanoseconds()给出以纳秒为单位的当前时间，用作种子。
下面是一个更通用的类，用于获取范围内的随机整数和日期:
#include <iostream>
#include <ctime>
#include <boost/random/mersenne_twister.hpp>
#include <boost/random/uniform_int_distribution.hpp>
#include <boost/random/variate_generator.hpp>
#include "boost/date_time/posix_time/posix_time.hpp"
#include "boost/date_time/gregorian/gregorian.hpp"
using namespace std;
using namespace boost;
using namespace boost::posix_time;
using namespace boost::gregorian;
class Randomizer {
private:
static const bool debug_mode = false;
random::mt19937 rng_;
// The private constructor so that the user can not directly instantiate
Randomizer() {
if(debug_mode==true){
this->rng_ = random::mt19937();
}else{
this->rng_ = random::mt19937(current_time_nanoseconds());
}
};
int current_time_nanoseconds(){
struct timespec tm;
clock_gettime(CLOCK_REALTIME, &tm);
return tm.tv_nsec;
}
// C++ 03
// ========
// Dont forget to declare these two. You want to make sure they
// are unacceptable otherwise you may accidentally get copies of
// your singleton appearing.
Randomizer(Randomizer const&); // Don't Implement
void operator=(Randomizer const&); // Don't implement
public:
static Randomizer& get_instance(){
// The only instance of the class is created at the first call get_instance ()
// and will be destroyed only when the program exits
static Randomizer instance;
return instance;
}
bool method() { return true; };
int rand(unsigned int floor, unsigned int ceil){
random::uniform_int_distribution<> rand_ = random::uniform_int_distribution<> (floor,ceil);
return (rand_(rng_));
}
// Is not considering the millisecons
time_duration rand_time_duration(){
boost::posix_time::time_duration floor(0, 0, 0, 0);
boost::posix_time::time_duration ceil(23, 59, 59, 0);
unsigned int rand_seconds = rand(floor.total_seconds(), ceil.total_seconds());
return seconds(rand_seconds);
}
date rand_date_from_epoch_to_now(){
date now = second_clock::local_time().date();
return rand_date_from_epoch_to_ceil(now);
}
date rand_date_from_epoch_to_ceil(date ceil_date){
date epoch = ptime(date(1970,1,1)).date();
return rand_date_in_interval(epoch, ceil_date);
}
date rand_date_in_interval(date floor_date, date ceil_date){
return rand_ptime_in_interval(ptime(floor_date), ptime(ceil_date)).date();
}
ptime rand_ptime_from_epoch_to_now(){
ptime now = second_clock::local_time();
return rand_ptime_from_epoch_to_ceil(now);
}
ptime rand_ptime_from_epoch_to_ceil(ptime ceil_date){
ptime epoch = ptime(date(1970,1,1));
return rand_ptime_in_interval(epoch, ceil_date);
}
ptime rand_ptime_in_interval(ptime floor_date, ptime ceil_date){
time_duration const diff = ceil_date - floor_date;
long long gap_seconds = diff.total_seconds();
long long step_seconds = Randomizer::get_instance().rand(0, gap_seconds);
return floor_date + seconds(step_seconds);
}
};
我知道如何在c++中生成随机数，而不使用任何标头，编译器intrinsic或任何东西。
#include <cstdio> // Just for printf
int main() {
auto val = new char[0x10000];
auto num = reinterpret_cast<unsigned long long>(val);
delete[] val;
num = num / 0x1000 % 10;
printf("%llu\n", num);
}
在运行一段时间后，我得到了以下数据:
0: 5268
1: 5284
2: 5279
3: 5242
4: 5191
5: 5135
6: 5183
7: 5236
8: 5372
9: 5343
看起来是随机的。
工作原理:
现代编译器使用ASLR(地址空间布局随机化)防止缓冲区溢出。 你可以不使用任何库生成一些随机数，这只是为了好玩。不要那样使用ASLR。
#include <iostream>
#include <cstdlib>
#include <ctime>
int main() {
srand(time(NULL));
int random_number = std::rand(); // rand() return a number between 0 and RAND_MAX
std::cout << random_number;
return 0;
}
http://en.cppreference.com/w/cpp/numeric/random/rand
为每个RUN文件随机
size_t randomGenerator(size_t min, size_t max) {
std::mt19937 rng;
rng.seed(std::random_device()());
//rng.seed(std::chrono::high_resolution_clock::now().time_since_epoch().count());
std::uniform_int_distribution<std::mt19937::result_type> dist(min, max);
return dist(rng);
}
