C++数据结构实战：结构体struct定义、访问、函数参数、指针与typedef别名

数组仅能聚合同类型数据，结构体（struct）可组合不同类型数据项，常用于表示记录。例：图书管理需记录标题、作者、主题、书号。

定义结构体

语法：

struct [结构体标签] {
    成员定义;
    ...
} [一个或多个结构体变量];

标签可选。成员定义即普通变量定义。定义Books结构：

struct Books {
    char title[50];
    char author[50];
    char subject[100];
    int book_id;
} book; // 可选变量声明

访问结构体成员

使用成员访问运算符.（点号）。示例：

#include <iostream>
#include <cstring>
using namespace std;
struct Books {
    char title[50];
    char author[50];
    char subject[100];
    int book_id;
};
int main() {
    struct Books Book1, Book2;
    strcpy(Book1.title, "Learn C++ Programming");
    strcpy(Book1.author, "Chand Miyan");
    strcpy(Book1.subject, "C++ Programming");
    Book1.book_id = 6495407;
    strcpy(Book2.title, "Telecom Billing");
    strcpy(Book2.author, "Yakit Singha");
    strcpy(Book2.subject, "Telecom");
    Book2.book_id = 6495700;
    cout << "Book 1 title : " << Book1.title << endl;
    cout << "Book 1 author : " << Book1.author << endl;
    cout << "Book 1 subject : " << Book1.subject << endl;
    cout << "Book 1 id : " << Book1.book_id << endl;
    cout << "Book 2 title : " << Book2.title << endl;
    cout << "Book 2 author : " << Book2.author << endl;
    cout << "Book 2 subject : " << Book2.subject << endl;
    cout << "Book 2 id : " << Book2.book_id << endl;
    return 0;
}

输出两本书完整信息。

结构体作为函数参数

传递方式同普通变量/指针。按值传递（拷贝副本）或传地址。示例封装printBook函数：

void printBook(struct Books book); // 声明
// ... 定义同前 ...
int main() {
    // ... 赋值同前 ...
    printBook(Book1);
    printBook(Book2);
    return 0;
}
void printBook(struct Books book) {
    cout << "Book title : " << book.title << endl;
    cout << "Book author : " << book.author << endl;
    cout << "Book subject : " << book.subject << endl;
    cout << "Book id : " << book.book_id << endl;
}

结构体指针

定义指针：struct Books *struct_pointer;
取地址：struct_pointer = &Book1;
通过指针访问成员用->运算符：struct_pointer->title;

重写printBook接受指针版本：

void printBook(struct Books *book) {
    cout << "Book title : " << book->title << endl;
    cout << "Book author : " << book->author << endl;
    cout << "Book subject : " << book->subject << endl;
    cout << "Book id : " << book->book_id << endl;
}
int main() {
    // ... 赋值同前 ...
    printBook(&Book1);
    printBook(&Book2);
    return 0;
}

输出结果相同。

typedef简化结构体使用

为结构体起别名，省去struct关键字：

typedef struct {
    char title[50];
    char author[50];
    char subject[100];
    int book_id;
} Books;
// 直接用Books定义变量
Books Book1, Book2;

typedef亦适用于非结构体：

typedef long int *pint32;
pint32 x, y, z; // 均为long int*类型