c中的结构体嵌套问题

Structures in C language are basically user-defined data types that enables the user to create a data type that can group elements of different data types into it.

C语言的结构基本上是用户定义的数据类型 ，使用户能够创建一个数据类型，该数据类型可以将不同数据类型的元素分组到其中 。

Thus, it contains different data types to be represented by a single Structure name.

因此，它包含由单个结构名称表示的不同数据类型。

用C创建结构 (Creating Structures in C)

C language uses the struct keyword to create a structure.

C语言使用struct关键字创建结构。

Syntax:

句法：


struct Structure_Name
{Datatype data_member1;Datatype data_member2;..Datatype data_memberN;
};

As mentioned above, C language uses the struct keyword to build a structure. Inside the curly brackets, the user can define the data members necessary to serve the purpose of the particular program. These data members are the basic C language variables of different data types such as int, float, double, char, etc.

如上所述，C语言使用struct关键字来构建结构。在大括号内，用户可以定义实现特定程序目的所需的数据成员。这些数据成员是不同数据类型（例如int，float，double，char等）的基本C语言变量。

It is mandatory to add a semi-colon (;) after the closing curly bracket of a particular structure.

强制在特定结构的右花括号后添加分号（;）。

Example:

例：


struct Student_info
{
char name[100];
char address[100];
char division[50];
int roll_num;
};

In the above code snippet, we have created a structure as Student_info to serve the purpose of Student Information. Within the structure, we have declared data members: name, address, division, and roll_num with their particular data type.

在上面的代码片段中，我们创建了一个名为Student_info的结构来满足学生信息的目的。在结构中，我们声明了数据成员： name ， address ， division和roll_num及其特定的数据类型。

声明结构变量 (Declaration of Structure Variables)

Structure Variables enable the user to access the data-members declared inside the structure.

使用结构变量 ，用户可以访问在结构内部声明的数据成员。

Either of the following ways can be used to declare Structure Variables in C:

可以使用以下任何一种方法在C中声明结构变量：

Declaration of Structure variables after the Structure definition在结构定义之后声明结构变量
Declaration of Structure variables along with the Structure definition结构变量的声明以及结构定义

1.在结构定义之后声明结构变量 (1. Declaration of Structure variables after the Structure definition)

Syntax:

句法：


struct Structure_Name
{Datatype data_member1;Datatype data_member2;..Datatype data_memberN;
};
struct Structure_Name Variable1, Variable2,.., VariableN;

Example:

例：


struct Student_info
{
char name[100];
char address[100];
char division[50];
int roll_num;
};
struct Student_info S1, S2;

In the above snippet of code, we have created Structure Variables S1 and S2 for the Structure Student_info after the declaration of the structure.

在上面的代码片段中，我们在结构声明后为结构Student_info创建了结构变量S1和S2 。

2.结构变量的声明以及结构定义 (2. Declaration of Structure variables along with the Structure definition)

Syntax:

句法：


struct Structure_Name
{Datatype data_member1;Datatype data_member2;..Datatype data_memberN;
} Structure_variable1, Structure_variable2;

Example:

例：


struct Student_info
{
char name[100];
char address[100];
char division[50];
int roll_num;
}S1, S2;

In the above piece of code, we have created the Structure Variables S1 and S2 along with the declaration of the structure Student_info.

在上面的代码中，我们创建了结构变量S1和S2以及结构Student_info的声明。

初始化结构数据成员 (Initializing Structure Data Members)

The C Structure data members cannot be initialized while declaring them. They need to be separately assigned values after the declaration of data members of the structure.

声明它们时，不能初始化C结构数据成员。在声明结构的数据成员之后，需要为它们分别分配值。

Example: Declaring Structure Data members while declaring them gives an error

示例：在声明结构数据成员的同时声明它们会产生错误


struct Student_info
{
char *name = "Safa"; // This statement gives compilation error
};

As mentioned above, the Structure data members need to be initialized separately after the declaration.

如上所述，在声明之后，需要分别初始化Structure数据成员。

Syntax:

句法：


Structure_Name.Structure_data_member_name = Value

访问结构中的数据成员 (Accessing data members in a Structure )

C uses the period or member access operator (.) to access the data members of the structure.

C使用句点或成员访问运算符（。）来访问结构的数据成员。

Syntax:

句法：


Structure_variable_name.Structure_data_member_name

Example:

例：


#include <stdio.h>struct Student_info
{
char *name;
char *address;
char *division;
int roll_num;
};int main()
{struct Student_info S1;S1.name = "Safa Mulani";S1.address = "Pune";S1.division = "A";S1.roll_num = 24105;printf("The Student Information is as follows:\n");printf("\nName: %s", S1.name);printf("\nAddress: %s", S1.address);printf("\nDivision: %s", S1.division);printf("\nRoll Number: %d", S1.roll_num);return 0;
}

Here, we have created variable S1 of type struct. Further, we have accessed the structure variables: name, address, division and roll_num using S1.

在这里，我们创建了类型为struct的变量S1。此外，我们已经使用S1访问了结构变量： name ， address ， division和roll_num 。

Output:

输出：


The Student Information is as follows:Name: Safa Mulani
Address: Pune
Division: A
Roll Number: 24105

结构数组 (Array of Structure)

C allows the users to use an array to represent the data elements of the Structure.

C允许用户使用数组来表示结构的数据元素。

Syntax:

句法：


struct Structure_Name array_name[size];

In the below snippet of code, we have created an array ‘S’ of structure Student_info with size = 3.

在下面的代码片段中，我们创建了一个结构为Student_info的大小为3的数组“ S” 。

Example:

例：


#include<stdio.h>struct Student_info
{
char name[100];
char division[50];
int roll_num;
};
void main()
{
struct Student_info S[3];for(int i = 0; i < 3; i++){printf("\nEnter Student Details:\n");printf("\nName:\t");scanf("%s", S[i].name);printf("\nDivision:\t");scanf("%s", S[i].division);printf("\nRoll Number:\t"); scanf("%d", &S[i].roll_num);}printf("\nStudent Information:\n");for(int i = 0; i < 3; i++){printf("\nName: %s", S[i].name);printf("\nRoll Number: %d", S[i].roll_num);printf("\nDivision: %s", S[i].division);}
}

Output:

输出：

Enter Student Details:Name: Safa
Division: A
Roll Number: 23105Enter Student Details:Name: Aman
Division: B
Roll Number:21042Enter Student Details:Name: Divya
Division: D
Roll Number: 2134Student Information:Name: Safa
Roll Number: 23105
Division: A
Name: Aman
Roll Number: 21042
Division: B
Name: Divya
Roll Number: 2134
Division: D

结构作为功能参数 (Structure as Function Parameters)

C enables programmers to pass a Structure as an argument to a function in a similar fashion of passing variables/arrays as arguments to functions.

C使程序员可以将结构作为参数传递给函数，方式类似于将变量/数组作为参数传递给函数。

Example:

例：


#include <stdio.h>
struct Evaluation
{char name[50];int score;
};void display_details(struct Evaluation e1);
int main()
{struct Evaluation e;printf("Name: ");scanf("%[^\n]%*c", e.name);printf("Score: ");scanf("%d", &e.score);display_details(e);   // passing structure as an argumentreturn 0;
}
void display_details(struct Evaluation e1)
{printf("\nEvaluation details.....\n");printf("Name: %s", e1.name);printf("\nScore: %d", e1.score);
}

Output:

输出：


Name: Safa
Score: 56Evaluation details.....
Name: Safa
Score: 56

嵌套结构 (Nested Structures)

Nested Structures in C basically defining one structure into another structure i.e. it permits one structure to have another structure as a variable.

C中的嵌套结构基本上将一个结构定义为另一个结构，即它允许一个结构具有另一个结构作为变量 。

Example:

例：


struct Student_info
{
char *name;
char *Branch_name;struct Evaluation{   char *division; int hsc_score;int ssc_score;int roll_num;        }eval;}student;

In the above snippet, We have created a structure Student_info wherein we have represented another structure Evaluation as a member of it.

在以上代码段中，我们创建了一个Student_info结构，其中我们代表了另一个结构Evaluation作为其成员。

You can access the nested structs using struct1_var.struct2_var.struct2_innervar

您可以使用struct1_var.struct2_var.struct2_innervar访问嵌套结构

For example, in the above example, we used student as struct 1 variable and eval for the nested struct. We can access the inner variables as student.eval.ssc_score;

例如，在上面的示例中，我们使用Student作为结构1变量，并使用eval来嵌套结构。我们可以将内部变量访问为student.eval.ssc_score;。

结构指针 (Pointers in Structure)

C allows us to have a pointer to a structure. The arrow (->) operator enables the user to access the data members of the structure having a pointer to it.

C允许我们有一个指向结构的指针。 箭头（->）运算符使用户可以访问具有指向它的结构的数据成员。

Syntax:

句法：


struct Structure_Name
{Datatype data_member1;Datatype data_member2;..Datatype data_memberN;
};int main()
{struct Structure_Name *pointer_name;
}

Example:

例：


#include<stdio.h>struct Student_info
{
char *name;
int roll_num;
};
int main()
{
struct Student_info *St, S;
St = &S;printf("\nEnter Student Details:\n");printf("\nName:\t");scanf("%s", St->name);printf("\nRoll Number:\t"); scanf("%d", &St-&gt;roll_num);printf("\nStudent Information:\n");printf("\nName: %s", St->name);printf("\nRoll Number: %d", St->roll_num);return 0;
}

Output:

输出：

Enter Student Details:Name:    SafaRoll Number:    1234Student Information:Name: Safa
Roll Number: 1234

结论 (Conclusion)

Thus, in this article, we have understood the concept of Structures in C language.

因此，在本文中，我们了解了C语言中的结构概念。

参考资料 (References)

Structures in C documentationC文档中的结构

翻译自: https://www.journaldev.com/34614/structures-in-c

c中的结构体嵌套问题