Generate a Random number every 2 seconds? C++ Srand - c++

Question

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.

Answer 1

Say t is the current time in seconds (time(0)). It is obvious that t changes once per second. Then t/2, because of rounding, changes every two seconds.

Answer 2

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;
}