C++硬币翻转程序错误

C++ Coin flip program error

本文关键字：错误 程序 翻转 硬币 C++      更新时间：2023-10-16

我正在尝试在掷硬币时计算连续的人头数。不幸的是，我的连续人头计数器没有正确递增。有什么想法吗？代码和样本输出如下：

#include <iostream>
#include <string>
#include "random.h"
using namespace std;
string FlipCoin (string flip);

int main() {
    string flip;
    int consecutiveHeads = 0;
    int totalFlips = 0;
    while (consecutiveHeads<3) {
        totalFlips++;
        if (FlipCoin(flip) == "heads") {
           consecutiveHeads++;
        } else {
            consecutiveHeads = 0;
        }
        cout <<totalFlips<<" "<< FlipCoin(flip) << " " << consecutiveHeads <<endl;
    }
    cout <<"It took "<< totalFlips <<" coin flips to get 3 consecutive heads."<< endl;
    return 0;
}

string FlipCoin(string flip) {
    if (randomChance(0.50)) {
        return "heads";
    } else {
        return "tails";
    }
}

输出：

1 heads 1
2 tails 0
3 tails 1
4 heads 2
5 heads 3
It took 5 coin flips to get 3 consecutive heads.

每次调用FlipCoin(flip)都会生成一个新的随机数。你叫它两次，所以它产生了两个不同的随机数。您应该调用FlipCoin(flip)一次，并将其存储在一个变量中。

...
string result = FlipCoin(flip);
if (result == "heads") {
    consecutiveHeads++;
} else
    consecutiveHeads = 0;
}
cout <<"It took "<< totalFlips <<" coin flips to get 3 consecutive heads."<< endl;
...

正如其他人提到的，main中的flip变量未初始化且未使用。最好删除它。建议您在FlipCoin函数中传递flip作为引用（使用&）。这肯定有用处，但没有必要。最简单的修订可能是：

string FlipCoin() {
    if (randomChance(0.50)) {
        return "heads";
    } else {
        return "tails";
    }
}

PS:如果从函数中删除flip参数，则还必须将每次出现的FlipCoin(flip);替换为FlipCoin();

问题是在每次迭代中调用FlipCoin()两次：第一次是与"heads"进行比较，然后再次显示发生了什么。你需要调用它一次，并将其放入一个变量中：

while (consecutiveHeads<3) {
    totalFlips++;
    string curFlip = FlipCoin(flip);
    if (curFlip == "heads") {
       consecutiveHeads++;
    } else {
        consecutiveHeads = 0;
    }
    cout <<totalFlips<<" "<< curFlip << " " << consecutiveHeads <<endl;
}

附言：FlipCoin()的论据是什么？

每次调用FlipCoin函数时都会翻转。因此，在while函数的每次迭代中翻转两次。您可以考虑通过flip作为FlipCoin:的参考

#include <iostream>
#include <string>
#include "random.h"
using namespace std;
void FlipCoin (string &flip);

int main() {
    string flip;
    int consecutiveHeads = 0;
    int totalFlips = 0;
    while (consecutiveHeads<3) {
        totalFlips++;
        FlipCoin(flip);
        if (flip == "heads") {
           consecutiveHeads++;
        } else {
            consecutiveHeads = 0;
        }
        cout <<totalFlips<<" "<< flip << " " << consecutiveHeads <<endl;
    }
    cout <<"It took "<< totalFlips <<" coin flips to get 3 consecutive heads."<< endl;
    return 0;
}

void FlipCoin(string &flip) {
    if (randomChance(0.50)) {
        flip = "heads";
    } else {
        flip = "tails";
    }
}
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