Question

我对c ++很新。作为一个项目，我正在重写我在python中编写的一个小游戏（我从来没有让它正常工作）。在编译期间，我收到此错误：错误：不匹配'operator - ='

我知道这个运算符存在于c ++中，为什么我会收到此错误？

代码：

void rpg() {
    cout << "This mode is not yet complete. It only contains a dungeon so far. I'm still working on the rest!";
    dgn();
}
void dgn() {
    int whp = 100;
    int mahp = 100;
    int hhp = 100;
    string m;
    int mhp;
    cout << "There are three passages. Do you take the first one, the second one, or the third one? (Give your answer in numbers)";
    int psg;
    cin >> psg;
    switch (psg) {
    case 1:
        m = "Troll";
        mhp = 80;
        break;
    case 2:
        m = "Goblin";
        mhp = 35;
        break;
    case 3:
        m = "Dragon";
        mhp = 120;
    }
    cout << "A ";
    cout << m;
    cout << " appears!";
    dgnrd(m, mhp, whp, mahp, hhp);
}

void dgnrd(string m, string mhp, int whp, int mahp, int hhp) {
    bool alive = true;
    while (alive) {
        string wa;
        string ma;
        string ha;
        cout << "What does Warrior do? ";
        cin >> wa;
        cout << "What does Mage do? ";
        cin >> ma;
        cout << "What does Healer do? ";
        cin >> ha;
        if (wa == "flameslash") {
            cout << "Warrior used Flame Slash!";
            mhp -= 20;
        }
        else if (wa == "dragonslash" && m == "Dragon") {
            cout << "Warrior used Dragon Slash!";
            mhp -= 80;
        }
        else if (wa == "dragonslash" && (m == "Troll" || m == "Goblin")) {
            cout << "Warrior's attack did no damage!";
        }
        if (ma == "icicledrop") {
            cout << "Mage used Icicle Drop!";
            mhp -= 30;
            mahp -= 10;
            whp -= 10;
            hhp -= 10;
        }
        else if (ma == "flamesofhell") {
            cout << "Mage used Flames of Hell!";
            mhp -= 75;
            mahp -= 50;
            whp -= 50;
            hhp -= 50;
        }
        else if (ma == "punch") {
            cout << "Mage used Punch!";
            mhp -= 5;
        }
    }
}

Answer 1

在dgn()中，您有

int mhp;

这是明智的，因为它是一个数字数量。

但是你的助手函数声明了

string mhp

参数列表中的

，它应该导致函数调用中实际和形式参数之间的类型不匹配错误

dgnrd(m, mhp, whp, mahp, hhp);

将其修复为int& mhp，并且会立即消除几个问题。

请注意&创建引用。这使得函数与其调用者共享变量，以便对调用者的副本进行更改。否则（按值传递）函数内的所有更改都会在函数返回时消失。

Answer 2

原因是std::string没有运营商-=。有+=，它附加到现有字符串，但运算符-=的语义不明确。

除了那个明显的问题，dgnrd函数的参数类型与传递它的参数的类型不匹配。

Answer 3

您似乎在字符串而不是int上运行 - =运算符。 mhp是string，因此以下语句导致编译错误：

mhp -=

c ++错误：'operator- ='不匹配

3 个答案: