为什么编译器告诉我没有运算符匹配我的 'if' 和 'else if' 语句中的操作数类型？

Question

这段代码有什么问题？我一直在尝试，但我不知道为什么我不能在if语句中使用=或==。

#include <vector>

#include <cstdlib>

#include <time.h>

using namespace std;

/* I am trying to make the program output a periodic t symbol

so then it asks the user what the element is */

void symbols(std::vector<std::string> alcalinos) {

alcalinos = { "H", "Li", "Na", "K", "Rb", "Cs", "Fr" };

std::string elemento;

cout << "Introduce el elemento correspondiente al símbolo(en minusculas) : \n";

srand(time(NULL));

int random = rand() % 7;

cout << alcalinos[random];

cin >> elemento;

if ((alcalinos = "H") && (elemento = "hidrogeno")) {

    cout << "correcto\n";

}

else if ((alcalinos = "Li") && (elemento = "litio")) {

    cout << "correcto\n";

}

else if ((alcalinos = "Na") && (elemento = "sodio")) {

    cout << "correcto\n";

}

else if ((alcalinos = "K") && (elemento = "potasio")) {

    cout << "correcto\n";

}

else if ((alcalinos = "Rb") && (elemento = "rubidio")) {

    cout << "correcto\n";

}

else if ((alcalinos = "Cs") && (elemento = "cesio")) {

    cout << "correcto\n";

}

else if ((alcalinos = "Fr") && (elemento = "francio")) {

    cout << "correcto\n";

}

else {

    cout << "incorrecto\n";

}





int main(); {

    void symbols();

        

     }

Answer 1

我一定心情不错，我已经添加评论指出你犯的错误

void symbols() { // no parameter for function

    // local declaration of vector instead of parameter
    std::vector<std::string> alcalinos = { "H", "Li", "Na", "K", "Rb", "Cs", "Fr" };

    std::string elemento;

    cout << "Introduce el elemento correspondiente al símbolo(en minusculas) : \n";


    int random = rand() % 7;

    cout << alcalinos[random];

    cin >> elemento;

    // compare alcalinos[random] not alcalinos
    // use == not =
    if ((alcalinos[random] == "H") && (elemento == "hidrogeno")) {  
        cout << "correcto\n";
    }
    else if ((alcalinos[random] == "Li") && (elemento == "litio")) {
        cout << "correcto\n";
    }
    else {
        cout << "incorrecto\n";
    }
} // missing }





int main() { // no ; after main()

    srand(time(NULL)); // seed RNG once in main

    symbols(); // no void before function call
}

当你犯这么多错误时，这意味着你试图一次编写太多代码。如果您是初学者，请逐字逐句地一次添加一行代码。并在添加的每一行之后测试代码。这样一来，您一次只能尝试解决 一个问题。你会发现这样更容易。

为什么编译器告诉我没有运算符匹配我的 'if' 和 'else if' 语句中的操作数类型？

Why does the compiler tell me that no operators match the operand type in my 'if' and 'else if' statements?

c++

windows

debugging

encoding

operators