C++ 中的 srand(time(NULL))

srand(time(NULL)) in C++

提问by user2766542

If I comment out the line with srand, the program will work, but there is no seed so the values will be the same each time. The assignment requires that I use rand, srand, and timeto have the dice function be completely random.

如果我用 注释掉该行srand，程序将运行，但没有种子，因此每次的值都相同。分配要求我使用rand, srand, 并使time骰子函数完全随机。

#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;

}

回答by dzada

Put srandin the main and call it once. You have to use the seed once to get all the results from a random sequence.

放入srandmain 并调用一次。您必须使用一次种子才能从随机序列中获取所有结果。

Here you restart the sequence every time you roll the dice.

每次掷骰子时，您都会在此处重新启动序列。

See the documentation for srand()

请参阅文档 srand()