C++ data structure full solution

C++ data structures

C/C++ arrays allow you to define variables that can store data items of the same type, but structures are another user-defined data type available in C++ that allow you to store data items of different types.

A structure is used to represent a record. Suppose you want to track the activity of books in the library. You may need to track the following properties of each book:

• Title: Title
• Author : author
• Subject : category
• Book ID: ID of the book

define structure

In order to define a structure, you must use the struct statement. The struct statement defines a new data type that contains multiple members. The format of the struct statement is as follows:

struct type_name {
    
    
member_type1 member_name1;
member_type2 member_name2;
member_type3 member_name3;
.
.
} object_names;

type_name is the name of the structure type, member_type1 member_name1 is a standard variable definition, such as int i; or float f; or other valid variable definitions. At the end of a structure definition, before the final semicolon, you can specify one or more structure variables, this is optional. The following is to declare a structure type Books , the variable is book :

struct type_name {
    
    
member_type1 member_name1;
member_type2 member_name2;
member_type3 member_name3;
.
.
} object_names;

access structure members

To access members of a structure, we use the member access operator (.) . The member access operator is a period between the structure variable name and the structure member we want to access.

The following example demonstrates the usage of the structure:

#include <iostream>
#include <cstring>
 
using namespace std;
 
// 声明一个结构体类型 Books 
struct Books
{
    
    
   char  title[50];
   char  author[50];
   char  subject[100];
   int   book_id;
};
 
int main( )
{
    
    
   Books Book1;        // 定义结构体类型 Books 的变量 Book1
   Books Book2;        // 定义结构体类型 Books 的变量 Book2
 
   // Book1 详述
   strcpy( Book1.title, "C++ 教程");
   strcpy( Book1.author, "Runoob"); 
   strcpy( Book1.subject, "编程语言");
   Book1.book_id = 12345;
 
   // Book2 详述
   strcpy( Book2.title, "CSS 教程");
   strcpy( Book2.author, "Runoob");
   strcpy( Book2.subject, "前端技术");
   Book2.book_id = 12346;
 
   // 输出 Book1 信息
   cout << "第一本书标题 : " << Book1.title <<endl;
   cout << "第一本书作者 : " << Book1.author <<endl;
   cout << "第一本书类目 : " << Book1.subject <<endl;
   cout << "第一本书 ID : " << Book1.book_id <<endl;
 
   // 输出 Book2 信息
   cout << "第二本书标题 : " << Book2.title <<endl;
   cout << "第二本书作者 : " << Book2.author <<endl;
   cout << "第二本书类目 : " << Book2.subject <<endl;
   cout << "第二本书 ID : " << Book2.book_id <<endl;
 
   return 0;
}

The example defines the structure type Books and its two variables Book1 and Book2. When the above code is compiled and executed, it produces the following result:

第一本书标题: C++教程
第一本书作者:Runoob
第一本书类目:编程语言
第一本书 ID :12345
第二本书标题: CSS 教程
第二本书作者:Runoob
第二本书类目:前端技术
第二本书 ID :12346

Structs as Function Arguments

You can use a structure as a function parameter, and the method of passing parameters is similar to other types of variables or pointers. You can use the above example to access structure variables:

#include <iostream>
#include <cstring>
 
using namespace std;
void printBook( struct Books book );
 
// 声明一个结构体类型 Books 
struct Books
{
    
    
   char  title[50];
   char  author[50];
   char  subject[100];
   int   book_id;
};
 
int main( )
{
    
    
   Books Book1;        // 定义结构体类型 Books 的变量 Book1
   Books Book2;        // 定义结构体类型 Books 的变量 Book2
 
    // Book1 详述
   strcpy( Book1.title, "C++ 教程");
   strcpy( Book1.author, "Runoob"); 
   strcpy( Book1.subject, "编程语言");
   Book1.book_id = 12345;
 
   // Book2 详述
   strcpy( Book2.title, "CSS 教程");
   strcpy( Book2.author, "Runoob");
   strcpy( Book2.subject, "前端技术");
   Book2.book_id = 12346;
 
   // 输出 Book1 信息
   printBook( Book1 );
 
   // 输出 Book2 信息
   printBook( Book2 );
 
   return 0;
}
void printBook( struct Books book )
{
    
    
   cout << "书标题 : " << book.title <<endl;
   cout << "书作者 : " << book.author <<endl;
   cout << "书类目 : " << book.subject <<endl;
   cout << "书 ID : " << book.book_id <<endl;
}

When the above code is compiled and executed, it produces the following result:

书标题: C++教程
书作者:Runoob
书类目:编程语言
书 ID :12345
书标题: CSS 教程
书作者:Runoob
书类目:前端技术
书 ID :12346

pointer to structure

You can define pointers to structures in a similar way to pointers to variables of other types, as follows:

structBooks*struct_pointer;

Now you can store the address of the structure variable in the above defined pointer variable. To find the address of a structure variable, put the & operator in front of the structure name, like this:

struct_pointer =&Book1;

In order to access a member of a struct using a pointer to that struct, you have to use the -> operator as follows:

struct_pointer->title;

Let us rewrite the above example using struct pointers, it will help you understand the concept of struct pointers:

#include <iostream>
#include <cstring>
 
using namespace std;
void printBook( struct Books *book );
 
struct Books
{
    
    
   char  title[50];
   char  author[50];
   char  subject[100];
   int   book_id;
};
 
int main( )
{
    
    
   Books Book1;        // 定义结构体类型 Books 的变量 Book1
   Books Book2;        // 定义结构体类型 Books 的变量 Book2
 
    // Book1 详述
   strcpy( Book1.title, "C++ 教程");
   strcpy( Book1.author, "Runoob"); 
   strcpy( Book1.subject, "编程语言");
   Book1.book_id = 12345;
 
   // Book2 详述
   strcpy( Book2.title, "CSS 教程");
   strcpy( Book2.author, "Runoob");
   strcpy( Book2.subject, "前端技术");
   Book2.book_id = 12346;
 
   // 通过传 Book1 的地址来输出 Book1 信息
   printBook( &Book1 );
 
   // 通过传 Book2 的地址来输出 Book2 信息
   printBook( &Book2 );
 
   return 0;
}
// 该函数以结构指针作为参数
void printBook( struct Books *book )
{
    
    
   cout << "书标题  : " << book->title <<endl;
   cout << "书作者 : " << book->author <<endl;
   cout << "书类目 : " << book->subject <<endl;
   cout << "书 ID : " << book->book_id <<endl;
}

When the above code is compiled and executed, it produces the following result:

书标题: C++教程
书作者:Runoob
书类目:编程语言
书 ID :12345
书标题: CSS 教程
书作者:Runoob
书类目:前端技术
书 ID :12346

typedef keyword

Here's a simpler way of defining structures where you can "alias" the type you create. For example:

typedefstructBooks
{
   char  title[50];
   char  author[50];
   char  subject[100];
   int   book_id;
}Books;

Now, you can use Books directly to define variables of type Books without using the struct keyword. Here is an example:

BooksBook1,Book2;

You can use the typedef keyword to define non-struct types as follows:

typedeflongint*pint32;
 
pint32 x, y, z;

x, y and z are all pointers to long int.