C++ Simple Dice roll - 如何返回多个不同的随机数 [英] C++ Simple Dice roll - how to return multiple different random numbers

问题描述

我对 C++ 很陌生，正在尝试使用 Die class/main 制作一个简单的骰子.

I am pretty new to C++ and am trying to make a simple die roll with a Die class/main.

我可以在 1-dieSize 范围内获得一个随机数，但是，每次我掷骰子"时，它只会给我相同的随机数.例如，当我掷骰子三次时，它会掷出 111 或 222 等，而不是 3 个不同的随机掷骰子.任何解释此问题的帮助将不胜感激！

I can get a random number within my range 1-dieSize, however, each time I "roll the dice" it just gives me the same random number. For example, when I roll this dice three times, it will cout 111 or 222 etc instead of 3 different random rolls. Any help explaining this issue would be much appreciated!

我的模头只是一个基本的头.我假设的问题是随机函数.

My die header is just a basic header. My issue I'm assuming is with the random function.

主要:

int main()
{
// Call menu to start the program
Die myDie(4);

cout << myDie.rollDie();
cout << myDie.rollDie(); // roll dice again
cout << myDie.rollDie(); // roll again


return 0;
}

die.cpp:

Die::Die(int N)
{
//set dieSize to the value of int N
this->dieSize = N;
}

int Die::rollDie()
{
    // Declaration of variables
int roll;
int min = 1; // the min number a die can roll is 1
int max = this->dieSize; // the max value is the die size

unsigned seed;
seed = time(0);
srand(seed);

roll = rand() % (max - min + 1) + min;

return roll;
}

在 die.cpp 中，我包含了 cstdlib 和 ctime.

In die.cpp I have the cstdlib and ctime included.

推荐答案

正如 melpomene 在评论中所建议的，您应该在程序的某个时刻只初始化一次随机的 seed.

As melpomene suggested in the comment you should initialize the seed of the random only once at some point of the program.

rand() 函数并不是真正的随机数创建器，而是对先前生成的值进行位操作的序列，它从种子生成的第一个值开始(调用 <代码>srand(种子)).

The rand() function is not really a random number creator, rather a sequence of bit manipulation on the previously generated value, which starts with the first value that is generated by the seed (calling srand(seed)).

#include <iostream>
#include <cstdlib>

int rollDie()
{
    int roll;
    int min = 1; // the min number a die can roll is 1
    int max = 6;// this->dieSize; // the max value is the die size

    roll = rand() % (max - min + 1) + min;

    return roll;
}

int main()
{
    srand(time(0));
    for(int i=0;i<10;i++)
    {
        std::cout << rollDie() << std::endl;
    }
}

很有可能你已经在使用 C++11，所以你应该阅读和练习随机库:http://en.cppreference.com/w/cpp/numeric/random

There is a good chance that you are already using C++11, so you should read and practice with the random library: http://en.cppreference.com/w/cpp/numeric/random

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