使用结构绑定更改自定义结构的值

Question

我正在尝试找到一种方法来使用结构化绑定来更改自定义结构的值。我能够使用 std::map。我参考了一些来自 Structured binding

在下面的代码中，我能够更改地图的值。我想将 unsigned salary 的值从默认的 1000 更改为 10000

#include<iostream>
#include<string>
#include<vector>
#include<map>

struct employee {
    unsigned id;
    int roll;
    std::string name;
    std::string role;
    unsigned salary=1000;
};
int main()
{
   std::map<std::string, int> animal_population {
        {"humans", 10},
        {"chickens", 11},
        {"camels", 12},
        {"sheep", 13},
    };
    std::cout<<"Before the change"<<'\n';
    for (const auto &[species, count] : animal_population)
    {
        std::cout << "There are " << count << " " << species
        << " on this planet.\n";
    }
    for (const auto &[species, count] : animal_population)
     {
        if (species=="humans")
        {
            animal_population[species]=2000;
        }

     }
     std::cout<<"After the change"<<'\n';
     for (const auto &[species, count] : animal_population)
     {
            std::cout << "There are " << count << " " << species
            << " on this planet.\n";
     }

    std::vector<employee> employees(4);
    employees[0].id = 1;
    employees[0].name = "hari";
    employees[1].id = 2;
    employees[1].name = "om";


    for (const auto &[id,roll,name,role,salary] : employees) {
        std::cout << "Name: " << name<<'\n'
        << "Role: " << role<<'\n'
        << "Salary: " << salary << '\n';
    }

}

输出

Before the change
There are 12 camels on this planet.
There are 11 chickens on this planet.
There are 10 humans on this planet.
There are 13 sheep on this planet.
After the change
There are 12 camels on this planet.
There are 11 chickens on this planet.
There are 2000 humans on this planet.
There are 13 sheep on this planet.
Name: hari
Role: 
Salary: 1000
Name: om
Role: 
Salary: 1000
Name: 
Role: 
Salary: 1000
Name: 
Role: 
Salary: 1000

改变我试图获得预期的输出

我收到错误

Cannot assign to variable 'salary' with const-qualified type 'const int'

for (const auto &[id,roll,name,role,salary] : employees) {
    //employees[].salary = 10000; //not working
    // salary = 10000;            //not working
    std::cout << "Name: " << name<<'\n'
    << "Role: " << role<<'\n'
    << "Salary: " << salary << '\n';
}

预期输出

Before the change
There are 12 camels on this planet.
There are 11 chickens on this planet.
There are 10 humans on this planet.
There are 13 sheep on this planet.
After the change
There are 12 camels on this planet.
There are 11 chickens on this planet.
There are 2000 humans on this planet.
There are 13 sheep on this planet.
Name: hari
Role: 
Salary: 10000
Name: om
Role: 
Salary: 10000
Name: 
Role: 
Salary: 10000
Name: 
Role: 
Salary: 10000

提前感谢任何解决方案和建议

Answer 1

问题是您的值有 const 个验证器。它们是不可修改的。

删除 const 并使用引用 & 以便您可以修改这些变量。

for (auto &[id,roll,name,role,salary] : employees) {
    salary = 10000;
    std::cout << "Name: " << name<<'\n'
    << "Role: " << role<<'\n'
    << "Salary: " << salary << '\n';
}

使用结构绑定更改自定义结构的值

Using structure binding to change the value of a custom structure

c++

c++17

structured-bindings