每2秒生成一个随机数？ C ++ Srand [英] Generate a Random number every 2 seconds? C++ Srand

问题描述

我正在学习C ++，为了做一个游戏，我能够使用srand的函数每秒生成一个随机数。但我想要的数字每2秒不同。

解决方案

这里是一个简单的方法来修复代码。

在无限中放置 clock（），而循环，并让时钟计数，以便当它达到两秒，它触发 rand（）生成一个新的随机数。重置 clock（）。

如你所知，delta时间是最后的时间，减去原始时间。

  dt = t  -  t0 
  

这个增量时间只是在 while 循环中经过的时间量。

a 函数的导数表示函数关于其中一个变量的无穷小变化。 deltaTime 。

函数关于变量的导数定义为 http://mathworld.wolfram.com/Derivative.html

  f（x + h）-f（x）
 f'（x）= lim ----------------- 
 h-> 0 h 
  

首先你得到一个时间， em> TimeZero = clock（），以供参考。

得到并通过 h 来实现。 h 是 CLOCKS_PER_SEC 。现在增量时间是

  deltaTime =（clock（） -  TimeZero）/ CLOCKS_PER_SEC; 
  

当 deltaTime>

将所有代码转换为代码结果：

  #include< cstdlib> 
 #include< ctime> 
 #include< iostream> 
 using namespace std; 
 
 int main（int argc，char * argv []）{
 cout< 每2秒生成一个新的随机数\\\
\\\
; 
 
 //创建时钟和启动计时器
 clock_t TimeZero = clock（）; //启动计时器
 
 double deltaTime = 0; 
 double secondsToDelay = 2; 
 bool exit = false; 
 
 //使用时间生成随机种子
 srand（time（0））; 
 
 while（！exit）{
 
 //获取以秒为单位的增量时间
 deltaTime =（clock（） -  TimeZero）/ CLOCKS_PER_SEC; 
 cout<< \b<< secondsToDelay-deltaTime< \b; 
 
 //比较delta时间是否为2秒或以上
 if（deltaTime> secondsToDelay）{
 cout< ; 
 
 //生成新的随机数
 int i = rand（）％100 + 1; 
 cout<< \\\
New random：<< i<< \\\
; 
 
 //复位时钟定时器
 deltaTime = clock（）; 
 TimeZero = clock（） 
} 
} 
 
 return 0; 
} 
  

I am studying C++ in order to make a game and I was able to generate a random number every second using the functions of srand. But I wanted the number to be different every 2 second instead.

解决方案

Here is a simple way to fix the code.

Put a clock() in an infinite while loop and let the clock count so that when it reaches two seconds, it triggers rand() to generate a new random number. Reset the clock(). Repeat infinitely.

Now the Math behind:

As you already know, delta time is the final time, minus the original time.

dt = t - t0

This delta time, though, is simply the amount of time that passes while in the while loop.

The derivative of a function represents an infinitesimal change in the function with respect to one of its variables. Our deltaTime.

The derivative of a function with respect to the variable is defined as http://mathworld.wolfram.com/Derivative.html

                f(x + h) - f(x)
f'(x) = lim    -----------------
        h->0           h

First you get a time, i.e TimeZero = clock() , for reference.

Then you subtract that time from a new time you just got and devide it by h. h is CLOCKS_PER_SEC. Now delta time is

deltaTime = (clock() - TimeZero) / CLOCKS_PER_SEC;

And when deltaTime > secondsToDelay, you generate a new random number.

Putting all that into code results in this:

#include <cstdlib>
#include <ctime>
#include <iostream>
using namespace std;

int main(int argc, char *argv[]){
    cout << "Generate a new random number every 2 seconds \n\n";

    // create a clock and start timer
    clock_t TimeZero = clock(); //Start timer

    double deltaTime = 0;
    double secondsToDelay = 2;
    bool exit = false;

    // generate random seed using time 
    srand(time(0)); 

    while(!exit) {

        // get delta time in seconds
        deltaTime = (clock() - TimeZero) / CLOCKS_PER_SEC;
        cout << "\b" << secondsToDelay - deltaTime << "\b";

         // compare if delta time is 2 or more seconds
        if(deltaTime > secondsToDelay){
            cout << "                      ";

            // generate new random number
            int i = rand() % 100 + 1; 
            cout << "\nNew random : " << i << "           \n"; 

            //reset the clock timers
            deltaTime = clock();
            TimeZero = clock();
        }
      }

    return 0;
}

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