srand（time（NULL））in C++

Question

如果我用srand註釋掉該行，該程序將工作，但沒有種子，因此每次的值都是相同的。該任務要求我使用rand,srand和time使骰子函數完全隨機。

#include <iostream> 
#include <cstdlib> 
#include <cmath> 
#include <ctime> 

using namespace std; 

int rollDice(); 
// function declaration that simulates the rolling of dice 

int main() { 

    int roll1 = rollDice(); 

    int roll2 = rollDice(); 

    // define, initialize, and combine dice roll total 

    int total; 

    total = 0; 

    total = roll1 + roll2; 

    * this is where a bunch of stuff is output to the screen from the dice rolls, using total as well as some other stuff that is being calculated, i left it out for simplicity* 

} 

// function to simulate a random dice roll 

int rollDice() { 

    int r; 

    srand (time(NULL)); 

    r = (rand() % 6) + 1; 

    return r; 

} 

Answer 1

把srand放在主中並調用一次。 您必須使用一次種子從隨機序列中獲取所有結果。

在這裏你每次擲骰子時重新開始序列。

見srand()