C++ 函数和奇怪的错误

Question

所以我正在用 C++ 编写一个小型的石头剪刀布游戏结构，但我遇到了一些我不理解的错误。

解决方案

函数 string numberToWord (int x) 不能在函数 main 中。由于编译器的工作方式，它必须是一个单独的方法。我只是将它移出然后它工作正常。

上一个问题

所以我正在用 C++ 编写一个小型的石头剪刀布游戏结构，但我遇到了一些我不理解的错误。

首先是代码需要一个';'在 NumberToWord 函数中，但它不应该，因为它是一个函数。

另一个错误是随机出现的它似乎不喜欢的 else 语句之一。

也许我遗漏了一些东西，我不知道，但这应该是一个简单的修复。

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

int main()
{
    int seed = static_cast <int> (time(0)); //Sets the random seed
    srand(seed);

    int winCount = 0;

    string numberToWord (int x) {
        string outputChoice;

        if (x == 0) { outputChoice = "Rock"; }
        else if (x == 1) { outputChoice = "Paper"; }
        else if (x == 2) { outputChoice = "Scissors"; }

        return outputChoice;
    }

    while (winCount < 3) {
        int computerChoice = rand() % 4;
        int userChoice;

        cout << userChoice << endl;

        cout << "Please Enter 0 for Rock, 1 for Paper, or 2 for Scissors: "; //Asks for user input
        cin >> userChoice; //Inputs user input to variable

        if (userChoice == computerChoice) {
            cout << "Compuer Choose: " << numberToWord(computerChoice) << endl;
            cout << "You Choose: " << numberToWord(userChoice) << endl;
            cout << "Draw!" << endl;
        }
        else if ((userChoice == 1) && (computerChoice == 2)) { //Rock v Paper
            cout << "Compuer Choose: " << numberToWord(computerChoice) << endl;
            cout << "You Choose: " << numberToWord(userChoice) << endl;
            cout << "Compuer wins!" << endl;
        }
        else if ((userChoice == 1) && (computerChoice == 3)) { //Rock v Scissors
            cout << "Compuer Choose: " << numberToWord(computerChoice) << endl;
            cout << "You Choose: " << numberToWord(userChoice) << endl;
            cout << "You win!" << endl;
            winCount += 1;
        }
        else if ((userChoice == 2) && (computerChoice == 1)) { //Paper v Rock
            cout << "Compuer Choose: " << numberToWord(computerChoice) << endl;
            cout << "You Choose: " << numberToWord(userChoice) << endl;
            cout << "You win!" << endl;
            winCount += 1;
        }
        else if ((userChoice == 2) && (computerChoice == 3)) { //Paper v Scissors
            cout << "Compuer Choose: " << numberToWord(computerChoice) << endl;
            cout << "You Choose: " << numberToWord(userChoice) << endl;
            cout << "Compuer wins!" << endl;
        }
        else if ((userChoice == 3) && (computerChoice == 1)) { //Scissors v Rock
            cout << "Compuer Choose: " << numberToWord(computerChoice) << endl;
            cout << "You Choose: " << numberToWord(userChoice) << endl;
            cout << "Compuer wins!" << endl;
        }
        else if ((userChoice == 3) && (computerChoice == 2)) { //Scissors v Paper
            cout << "Compuer Choose: " << numberToWord(computerChoice) << endl;
            cout << "You Choose: " << numberToWord(userChoice) << endl;
            cout << "You win!" << endl;
            winCount += 1;
        }
    }


    return 0;
}

感谢您的所有帮助！

---

第 2 部分

简单地说程序不喜欢'

参考资料：

http://www.cplusplus.com/doc/tutorial/basic_io/

http://www.cplusplus.com/doc/tutorial/variables/

void displayOutput(int comp, int user, string winner) {
    string compOutputChoice = "";
    string userOutputChoice = "";

    /*
    if (comp == 0) { compOutputChoice = "Rock"; }
    else if (comp == 1) { compOutputChoice = "Paper"; }
    else if (comp == 2) { compOutputChoice = "Scissors"; }

    if (user == 0) { userOutputChoice = "Rock"; }
    else if (user == 1) { userOutputChoice = "Paper"; }
    else if (user == 2) { userOutputChoice = "Scissors"; }
    */

    cout << "Compuer Choose: " << compOutputChoice << endl;
    cout << "You Choose: " << userOutputChoice << endl;
    //cout << winner << endl;

    return;
}

错误：

错误（活动）没有操作符“

错误（活动）没有运算符“

错误 C2679 二进制“

错误 C2679 二进制“

Answer 1

函数string numberToWord (int x) 嵌套在main 函数内。那不是有效的 C++。

GCC 编译器确实支持嵌套函数作为扩展，但它不是标准的一部分，其他编译器（据我所知）不接受它。只是不要那样做。将函数移出 main（或者，如果有意义，将其设为 lambda）。

Answer 2

问题很简单。 numberToWord 不能是 main 的内部函数。如果您使用的是较新的 C++，请将其移到 main 之外或将其更改为 lambda。

auto numberToWord = [](int x) -> string {
    string outputChoice;

    if (x == 0) { outputChoice = "Rock"; }
    else if (x == 1) { outputChoice = "Paper"; }
    else if (x == 2) { outputChoice = "Scissors"; }

    return outputChoice;
};