C 中的嵌套结构用法

Question

来自下面给出的片段。

            typedef struct {
                int Code;
                int ParentCode;
            }TypeStudentConfidential;

            typedef struct {
                int age;
                int RollNo;
                int Rank;
                char Name[10];
            }TypeStudent;

            typedef struct {
                char class_name[20];
                //XXXXXXXXXXXXXXXXX //How could I declare the TypeClass element here?
            }TypeClass;

            int main()
            {

               const TypeStudent  Stu_Details[] = {
                 { 3,   1,  18, "Mahesh"},
                 { 3,   1,   7,  "Kumar"}
               };

               const TypeStudentConfidential Conf_Details[] = {
                 { 761, 814},
                 { 124, 562}
               };

               const TypeClass Class_Details[]= {
                 { "Class 10",     Stu_Details},  //struct TypeStudent data
                 { "Class 8",     Conf_Details}   //struct TypeStudentConfidential data
               };

               return 0;
            }

问题：

1) 如何定义XXXXXX标记的typedef结构元素

2) 如何从 Class_Details 访问 XXXXXX 标记的元素

Answer 1

typedef struct TypeClass {
    char class_name[20];
    struct TypeStudent* type;
} TypeClass;

并访问

Typeclass a = {"classA", NULL};
Typeclass b = {"classB", NULL};
a.type = &b;
printf("%s\n", a.type->class_name); //prints b's classname

现在，如果您希望 XXXXXXXXXX 成为 TypeStudent 或 TypeStudentConfidential（正如您的代码片段所暗示的那样），您可能需要使用 union，如下所示：

#include <stdio.h>


typedef struct TypeClass{
        char class_name[20];
        union type {
                struct TypeStudent* students;
                struct TypeStudentConfidential* studentConfs;
        } type;
} TypeClass;

typedef struct TypeStudent {
        int age;
        int RollNo;
        int Rank;
        char Name[10];
} TypeStudent;

typedef struct TypeStudentConfidential {
        int Code;
        int ParentCode;
} TypeStudentConfidential;

int main() {
        //TypeClass a[2] = {{"C0", {NULL}}, {"C1", {NULL}}};

        TypeStudent studs[2]  = {{10, 10, 10, "Joe"}, {5, 5, 5, "Bob"}};
        TypeStudentConfidential confs[2]  = {{1, 2}, {3, 4}};

        TypeClass a[2] = {{"C0", {.students = studs}}, {"C1", {.studentConfs = confs}}};

        //a[0].type.students = studs;
        //a[1].type.studentConfs = confs;

        printf("%s, %s\n", a[0].type.students->Name, (a[0].type.students + 1)->Name);
        printf("%i, %i\n", a[1].type.studentConfs->Code, (a[1].type.studentConfs + 1)->Code);
        return 0;
}

C 中的嵌套结构用法

Nested Structure Usage in C

c

typedef

nested

structure