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

本文关键字：结构 自定义 绑定      更新时间：2023-10-16

我正在尝试找到一种使用结构化绑定更改自定义结构值的方法。我能够用std::map.我参考了一些材料 结构化绑定

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

更改我试图获得预期的输出

我得到的错误

不能分配给具有常量合格类型"const 的变量"薪水" 国际'

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

问题是你的值constcvalifier。它们是不可修改的。

删除const并使用引用&以便可以修改这些变量。

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