C++结构体完全攻略（超详细）

• 使用关键字 struct 而不是关键字 class。
• 尽管结构体可以包含成员函数，但它们很少这样做。所以，通常情况下结构体声明只会声明成员变量。
• 结构体声明通常不包括 public 或 private 的访问修饰符。
• 类成员默认情况是私有的，而结构体的成员则默认为 public。程序员通常希望它们保持公开，只需使用默认值即可。

C++ 中保留了C语言的 struct 关键字，struct 和 class 基本是通用的，只有几个细节不同，感兴趣的小伙伴请猛击这里了解详情。

struct PayRoll
{
    int empNumber;
    string name;
    double hours,payRate,grossPay;
};

PayRoll deptHead, foreman, associate;

初始化结构体

初始化列表

struct Date
{
    int day, month, year;
};

Date birthday = {23, 8, 1983};

Date birthday = {23,8};

Date birthday = {23,1983}; //非法

//非法结构体声明
struct Date
{
    int day = 23,
    month = 8,
    year = 1983;
}；

构造函数初始化结构体

1. 如果有某个成员未被初始化，那么在这种情况下，跟随在该成员后面的成员都不能初始化。
2. 如果结构体包括任何诸如字符串之类的对象，那么在许多编译器上它都将无法运行。

struct Employee
{
    string name;    // 员工姓名
    int vacationDays,    // 允许的年假
    daysUsed;    //已使用的年假天数
    Employee (string n ="",int d = 0)    // 构造函数
    {
        name = n;
        vacationDays = 10;
        daysUsed = d;
    }
};

访问结构体成员

deptHead.empNumber = 475;
foreman.empNumber = 897;
associate.empNumber = 729;

cout << deptHead.empNumber << endl;
cout << deptHead.name << endl;
cout << deptHead.hours << endl;
cout << deptHead.payRate << endl;
cout << deptHead.grossPay << endl;

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

struct PayRoll
{
    int    empNumber; // Employee number
    string name;    // Employee name
    double hours,    // Hours worked
    payRate; // Hourly pay rate
};

int main()
{
    PayRoll employee; // Employee is a PayRoll structure
    double grossPay; // Gross amount the employee earned this week
    cout << "Enter the employee1s number:";
    cin >> employee.empNumber;
    cout << "Enter the employee's name: ";
    cin.ignore();// Skip the '\n' character left in the input buffer
    getline(cin, employee.name);
    cout << "Hours worked this week: ";
    cin >> employee.hours;
    cout << "Employee's hourly pay rate: ";
    cin >> employee.payRate;
   
    // Calculate the employee's gross pay
    grossPay = employee.hours * employee.payRate;
    // Display the results
    cout << "\nHere is the employee1s payroll data:\n";
    cout << "Name:    " << employee.name << endl;
    cout << "Employee number: " << employee.empNumber << endl;
    cout << "Hours worked:    " << employee.hours << endl;
    cout << "Hourly pay rate: " << employee.payRate << endl;
    cout << fixed << showpoint << setprecision(2);
    cout << "Gross pay: $" << grossPay << endl;
    return 0;
}

Enter the employee1s number:2214
Enter the employee's name: Jack Smith
Hours worked this week: 40
Employee's hourly pay rate: 12.50

Here is the employee1s payroll data:
Name:   Jack Smith
Employee number: 2214
Hours worked:   40
Hourly pay rate: 12.5
Gross pay: $500.00

cin >> employee.empNumber; //正确

cin >> Payroll.empNumber; //错误

结构体嵌套

struct Costs
{
    double wholesale;
    double retail;
};

struct Item
{
    string partNum;
    string description;
    Costs pricing;
};

widget.partnum = "123A";
widget.description = "iron widget";
widget.pricing.wholesale = 100.0;
widget.pricing.retail = 150.0;

cout << widget.retail;    // 错误
cout << widget.Costs.wholesale;    // 错误

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

struct CostInfo
{
    double food, // Food costs
    medical, // Medical costs
    license, // License fee
    misc; // Miscellaneous costs
};
struct PetInfo
{
    string name; // Pet name
    string type; // Pet type
    int age; // Pet age
    CostInfo cost;
    PetInfo() // Default constructor
    {
        name = "unknown";
        type = "unknown";
        age = 0;
        cost.food = cost.medical = cost.license = cost.misc = 0.00;
    }
};

int main()
{
    PetInfo pet;
    pet.name = "Sassy";
    pet.type = "cat";
    pet.age = 5;
    pet.cost.food = 300.00;
    pet.cost.medical = 200.00;
    pet.cost.license = 7.00;
    cout << fixed << showpoint << setprecision(2);
    cout << "Annual costs for my " << pet.age << "—year—old "<< pet.type << " " << pet.name << " are $"<< (pet.cost.food + pet.cost.medical +pet.cost.license + pet.cost.misc) << endl;
    return 0;
}

程序输出结果：
Annual costs for my 5-year-old cat Sassy are $507.00

将结构体传递给函数

//程序1
#include <iostream>
#include <iomanip>
#include <string>
using namespace std;

struct Invltem// Holds data for an inventory item
{
    int partNum; // Part number
    string description; // Item description
    int onHand; // Units on hand
    double price; // Unit price
};
// Function prototypes
void getltemData(InvItem &) ;

void showItem(const InvItem &);

int main()
{
    InvItem part; // Define an Invltem structure variable.
    getItemData(part);
    showItem(part);
    return 0;
}

void getItemData(InvItem &item)
{
    cout << "Enter the part number: ";
    cin >> item.partNum;
    cout << "Enter the part description: ";
    cin.get();
    getline (cin, item.description);
    cout << "Enter the quantity on hand: ";
    cin >> item.onHand;
    cout << "Enter the unit price: ";
    cin >> item.price;
}
void showItem(const InvItem &item)
{
    cout << fixed << showpoint << setprecision(2) << endl;
    cout << "Part Number : " << item.partNum << endl;
    cout << "Description : " << item.description << endl;
    cout << "Units On Hand : " << item.onHand << endl;
    cout << "Price    : $" << item.price << endl;
}

Enter the part number: 800
Enter the part description: Screwdriver
Enter the quantity on hand: 135
Enter the unit price: 1.25

Part Number : 800
Description : Screwdriver
Units On Hand: 135
Price : $1.25

从函数返回一个结构体

InvItem getItemData()
{
    InvItem item;
    cout << "Enter the part number:";
    cin >> item.partNum;
    cout << "Enter the part description: ";
    cin.get();
    getline(cin, item.description);
    cout << "Enter the quantity on hand: ";
    cin >> item.onHand;
    cout << "Enter the unit price: ";
    cin >> item.price;
    return item;
}

part = getItemData();

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