add 7 exercises

data/3.C语言高阶/1.结构体/1.结构体简介/config.json

 {
-  "node_id": "569d5e11c4fc5de7844053d9a733c5e8",
-  "keywords": [
-    "结构体",
-    "C语言"
-  ],
-  "children": [],
-  "export": []
+    "node_id": "569d5e11c4fc5de7844053d9a733c5e8",
+    "keywords": [
+        "结构体",
+        "C语言"
+    ],
+    "children": [],
+    "export": [
+        "structures.json"
+    ]
 }
\ No newline at end of file

data/3.C语言高阶/1.结构体/1.结构体简介/structures.c

+#include <stdio.h>
+
+struct Student
+{
+    char *name;
+    int id;
+    unsigned int age;
+    char group;
+    float score;
+}
+
+int main()
+{
+    struct Student stu;
+    stu.name = "张三";
+    stu.id = 1001;
+    stu.age = 16;
+    stu.group = 'A';
+    stu.score = 95.50;
+
+    printf("========== 学生基本信息 ==========\n");
+    printf("姓名：%s\n学号：%d\n年龄：%d\n所在小组：%c\n成绩：%.2f\n",
+           stu.name, stu.id, stu.age, stu.group, stu.score);
+    printf("==================================\n");
+
+    return 0;
+}
\ No newline at end of file

data/3.C语言高阶/1.结构体/1.结构体简介/structures.json

+{
+    "type": "code_options",
+    "author": "卢昕",
+    "source": "structures.md",
+    "exercise_id":"51df13a16d96417bb5dbe6476c1ec05f"
+}
\ No newline at end of file

data/3.C语言高阶/1.结构体/1.结构体简介/structures.md

+# 结构体的定义与使用
+
+定义一个学生结构体，并实例化一个学生对象，保存一个学生的基本信息，最后输出该学生信息。请选出错误答案。
+
+## 答案
+```c
+#include <stdio.h>
+
+struct Student
+{
+    char *name;
+    int id;
+    unsigned int age;
+    char group;
+    float score;
+}
+
+int main()
+{
+    struct Student stu;
+    stu.name = "张三";
+    stu.id = 1001;
+    stu.age = 16;
+    stu.group = 'A';
+    stu.score = 95.50;
+
+    printf("========== 学生基本信息 ==========\n");
+    printf("姓名：%s\n学号：%d\n年龄：%d\n所在小组：%c\n成绩：%.2f\n",
+           stu.name, stu.id, stu.age, stu.group, stu.score);
+    printf("==================================\n");
+
+    return 0;
+}
+```
+
+## 选项
+### A
+```c
+#include <stdio.h>
+
+struct Student
+{
+    char *name;
+    int id;
+    unsigned int age;
+    char group;
+    float score;
+};
+
+int main()
+{
+    struct Student stu = {"张三", 1001, 16, 'A', 95.50};
+
+    printf("========== 学生基本信息 ==========\n");
+    printf("姓名：%s\n学号：%d\n年龄：%d\n所在小组：%c\n成绩：%.2f\n",
+           stu.name, stu.id, stu.age, stu.group, stu.score);
+    printf("==================================\n");
+
+    return 0;
+}
+```
+
+### B
+```c
+#include <stdio.h>
+
+struct Student
+{
+    char *name;
+    int id;
+    unsigned int age;
+    char group;
+    float score;
+} stu = {"张三", 1001, 16, 'A', 95.50};
+
+int main()
+{
+    printf("========== 学生基本信息 ==========\n");
+    printf("姓名：%s\n学号：%d\n年龄：%d\n所在小组：%c\n成绩：%.2f\n",
+           stu.name, stu.id, stu.age, stu.group, stu.score);
+    printf("==================================\n");
+
+    return 0;
+}
+```
+
+### C
+```c
+#include <stdio.h>
+
+typedef struct
+{
+    char *name;
+    int id;
+    unsigned int age;
+    char group;
+    float score;
+} Student;
+
+int main()
+{
+    Student stu = {"张三", 1001, 16, 'A', 95.50};
+
+    printf("========== 学生基本信息 ==========\n");
+    printf("姓名：%s\n学号：%d\n年龄：%d\n所在小组：%c\n成绩：%.2f\n",
+           stu.name, stu.id, stu.age, stu.group, stu.score);
+    printf("==================================\n");
+
+    return 0;
+}
+```

data/3.C语言高阶/1.结构体/2.结构体数组/config.json

@@ -5,5 +5,7 @@
     "C语言"
   ],
   "children": [],
-  "export": []
+  "export": [
+    "structures_array.json"
+  ]
 }
\ No newline at end of file

data/3.C语言高阶/1.结构体/2.结构体数组/structures_array.c

+#include <stdio.h>
+#define NUM_STR 3
+
+struct Student
+{
+    char *name;
+    int id;
+    unsigned int age;
+    char group;
+    float score;
+} cls[NUM_STR];
+
+int main()
+{
+    cls = {
+        {"张三", 1001, 16, 'A', 95.50},
+        {"李四", 1002, 15, 'A', 90.00},
+        {"王五", 1003, 16, 'B', 80.50}
+    };
+    
+    float total = 0, average = 0;
+    printf("=============== 学生基本信息 ===============\n");
+    printf("姓名\t学号\t年龄\t小组\t成绩\n");
+    printf("--------------------------------------------\n");
+    for (int i = 0; i < NUM_STR; ++i) {
+        printf("%s\t%d\t%d\t%c\t%.2f\n", 
+            cls[i].name, cls[i].id, cls[i].age, cls[i].group, cls[i].score);
+        total += cls[i].score;
+    }
+    printf("============================================\n");
+    average = total / NUM_STR;
+    printf("班级平均成绩：%.2f", average);
+
+    return 0;
+}
\ No newline at end of file

data/3.C语言高阶/1.结构体/2.结构体数组/structures_array.json

+{
+    "type": "code_options",
+    "author": "卢昕",
+    "source": "structures_array.md",
+    "exercise_id":"ce458884b396456d8b9993004272720e"
+}
\ No newline at end of file

data/3.C语言高阶/1.结构体/2.结构体数组/structures_array.md

+# 结构体数组
+
+定义一个学生结构体，并实例化一个结构体数组，用于保存一个班级所有学生的基本信息，最后输出所有学生基本信息，以及班级的学生平均成绩。请选出错误答案。
+
+## 答案
+```c
+#include <stdio.h>
+#define NUM_STR 3
+
+struct Student
+{
+    char *name;
+    int id;
+    unsigned int age;
+    char group;
+    float score;
+} cls[NUM_STR];
+
+int main()
+{
+    cls = {
+        {"张三", 1001, 16, 'A', 95.50},
+        {"李四", 1002, 15, 'A', 90.00},
+        {"王五", 1003, 16, 'B', 80.50}
+    };
+    
+    float total = 0, average = 0;
+    printf("=============== 学生基本信息 ===============\n");
+    printf("姓名\t学号\t年龄\t小组\t成绩\n");
+    printf("--------------------------------------------\n");
+    for (int i = 0; i < NUM_STR; ++i) {
+        printf("%s\t%d\t%d\t%c\t%.2f\n", 
+            cls[i].name, cls[i].id, cls[i].age, cls[i].group, cls[i].score);
+        total += cls[i].score;
+    }
+    printf("============================================\n");
+    average = total / NUM_STR;
+    printf("班级平均成绩：%.2f", average);
+
+    return 0;
+}
+```
+
+## 选项
+### A
+```c
+#include <stdio.h>
+
+struct Student
+{
+    char *name;
+    int id;
+    unsigned int age;
+    char group;
+    float score;
+} cls[] = {
+    {"张三", 1001, 16, 'A', 95.50},
+    {"李四", 1002, 15, 'A', 90.00},
+    {"王五", 1003, 16, 'B', 80.50}
+};
+
+int main()
+{
+    size_t i, num_stu = sizeof(cls) / sizeof(struct Student);
+    float total = 0, average = 0;
+    printf("=============== 学生基本信息 ===============\n");
+    printf("姓名\t学号\t年龄\t小组\t成绩\n");
+    printf("--------------------------------------------\n");
+    for (i = 0; i < num_stu; ++i) {
+        printf("%s\t%d\t%d\t%c\t%.2f\n", 
+            cls[i].name, cls[i].id, cls[i].age, cls[i].group, cls[i].score);
+        total += cls[i].score;
+    }
+    printf("============================================\n");
+    average = total / num_stu;
+    printf("班级平均成绩：%.2f", average);
+
+    return 0;
+}
+```
+
+### B
+```c
+#include <stdio.h>
+
+struct Student
+{
+    char *name;
+    int id;
+    unsigned int age;
+    char group;
+    float score;
+} cls[] = {
+    "张三", 1001, 16, 'A', 95.50,
+    "李四", 1002, 15, 'A', 90.00,
+    "王五", 1003, 16, 'B', 80.50
+};
+
+int main()
+{
+    size_t i, num_stu = sizeof(cls) / sizeof(struct Student);
+    float total = 0, average = 0;
+    printf("=============== 学生基本信息 ===============\n");
+    printf("姓名\t学号\t年龄\t小组\t成绩\n");
+    printf("--------------------------------------------\n");
+    for (i = 0; i < num_stu; ++i) {
+        printf("%s\t%d\t%d\t%c\t%.2f\n", 
+            cls[i].name, cls[i].id, cls[i].age, cls[i].group, cls[i].score);
+        total += cls[i].score;
+    }
+    printf("============================================\n");
+    average = total / num_stu;
+    printf("班级平均成绩：%.2f", average);
+
+    return 0;
+}
+```
+
+### C
+```c
+#include <stdio.h>
+
+struct Student
+{
+    char *name;
+    int id;
+    unsigned int age;
+    char group;
+    float score;
+} cls[] = {
+    {.name = "张三", .group = 'A', .age = 16, .score = 95.50, .id = 1001},
+    {.age = 15, .score = 90.00, .group = 'A', .id = 1002, .name = "李四"},
+    {.group = 'B', .age = 16, .name = "王五", .score = 80.50, .id = 1003}
+};
+
+int main()
+{
+    size_t i, num_stu = sizeof(cls) / sizeof(struct Student);
+    float total = 0, average = 0;
+    printf("=============== 学生基本信息 ===============\n");
+    printf("姓名\t学号\t年龄\t小组\t成绩\n");
+    printf("--------------------------------------------\n");
+    for (i = 0; i < num_stu; ++i) {
+        printf("%s\t%d\t%d\t%c\t%.2f\n", 
+            cls[i].name, cls[i].id, cls[i].age, cls[i].group, cls[i].score);
+        total += cls[i].score;
+    }
+    printf("============================================\n");
+    average = total / num_stu;
+    printf("班级平均成绩：%.2f", average);
+
+    return 0;
+}
+```

data/3.C语言高阶/1.结构体/3.结构体指针/config.json

 {
-  "node_id": "569d5e11c4fc5de7844053d9a733c5e8",
-  "keywords": [
-    "结构体",
-    "C语言"
-  ],
-  "children": [],
-  "export": []
+    "node_id": "569d5e11c4fc5de7844053d9a733c5e8",
+    "keywords": [
+        "结构体",
+        "C语言"
+    ],
+    "children": [],
+    "export": [
+        "structures_pointers.json"
+    ]
 }
\ No newline at end of file

data/3.C语言高阶/1.结构体/3.结构体指针/structures_pointers.c

+#include <stdio.h>
+
+typedef struct
+{
+    char *name;
+    int id;
+    unsigned int age;
+    char group;
+    float score;
+} Student;
+
+int main()
+{
+    Student stu = {"张三", 1001, 16, 'A', 95.50};
+    Student *stu_prt = &stu;
+
+    printf("========== 学生基本信息 ==========\n");
+    printf("姓名：%s\n学号：%d\n年龄：%d\n所在小组：%c\n成绩：%.2f\n",
+           *stu_prt.name, *stu_prt.id, *stu_prt.age, *stu_prt.group, *stu_prt.score);
+    printf("==================================\n");
+
+    return 0;
+}
\ No newline at end of file

data/3.C语言高阶/1.结构体/3.结构体指针/structures_pointers.json

+{
+    "type": "code_options",
+    "author": "卢昕",
+    "source": "structures_pointers.md",
+    "exercise_id":"5fe2bafbe9974e62bf3544e50aefa3cc"
+}
\ No newline at end of file

data/3.C语言高阶/1.结构体/3.结构体指针/structures_pointers.md

+# 结构体指针
+
+定义一个学生结构体，并实例化一个学生对象，保存一个学生的基本信息，最后使用结构体指针访问和输出该学生信息。请选出错误答案。
+
+
+## 答案
+```c
+#include <stdio.h>
+
+typedef struct
+{
+    char *name;
+    int id;
+    unsigned int age;
+    char group;
+    float score;
+} Student;
+
+int main()
+{
+    Student stu = {"张三", 1001, 16, 'A', 95.50};
+    Student *stu_prt = &stu;
+
+    printf("========== 学生基本信息 ==========\n");
+    printf("姓名：%s\n学号：%d\n年龄：%d\n所在小组：%c\n成绩：%.2f\n",
+           *stu_prt.name, *stu_prt.id, *stu_prt.age, *stu_prt.group, *stu_prt.score);
+    printf("==================================\n");
+
+    return 0;
+}
+```
+
+## 选项
+### A
+```c
+#include <stdio.h>
+
+typedef struct
+{
+    char *name;
+    int id;
+    unsigned int age;
+    char group;
+    float score;
+} Student;
+
+int main()
+{
+    Student stu = {"张三", 1001, 16, 'A', 95.50};
+    Student *stu_prt = &stu;
+
+    printf("========== 学生基本信息 ==========\n");
+    printf("姓名：%s\n学号：%d\n年龄：%d\n所在小组：%c\n成绩：%.2f\n",
+           stu_prt->name, stu_prt->id, stu_prt->age, stu_prt->group, stu_prt->score);
+    printf("==================================\n");
+
+    return 0;
+}
+```
+
+### B
+```c
+#include <stdio.h>
+
+struct
+{
+    char *name;
+    int id;
+    unsigned int age;
+    char group;
+    float score;
+} stu = {"张三", 1001, 16, 'A', 95.50}, *stu_prt = &stu;
+
+int main()
+{
+    printf("========== 学生基本信息 ==========\n");
+    printf("姓名：%s\n学号：%d\n年龄：%d\n所在小组：%c\n成绩：%.2f\n",
+           stu_prt->name, stu_prt->id, stu_prt->age, stu_prt->group, stu_prt->score);
+    printf("==================================\n");
+
+    return 0;
+}
+```
+
+### C
+```c
+#include <stdio.h>
+
+typedef struct
+{
+    char *name;
+    int id;
+    unsigned int age;
+    char group;
+    float score;
+} Student;
+
+int main()
+{
+    Student stu;
+    Student *stu_prt = &stu;
+    stu_prt->name = "张三";
+    stu_prt->id = 1001;
+    stu_prt->age = 16;
+    stu_prt->group = 'A';
+    stu_prt->score = 95.50;
+
+    printf("========== 学生基本信息 ==========\n");
+    printf("姓名：%s\n学号：%d\n年龄：%d\n所在小组：%c\n成绩：%.2f\n",
+           stu_prt->name, stu_prt->id, stu_prt->age, stu_prt->group, stu_prt->score);
+    printf("==================================\n");
+
+    return 0;
+}
+```

data/3.C语言高阶/1.结构体/4.结构体与函数/config.json

@@ -5,5 +5,5 @@
     "C语言"
   ],
   "children": [],
-  "export": []
+  "export": ["structures_n_func.json"]
 }
\ No newline at end of file

data/3.C语言高阶/1.结构体/4.结构体与函数/structures_n_func.c

+#include <stdio.h>
+
+typedef struct
+{
+    char *name;
+    int id;
+    unsigned int age;
+    char group;
+    float score;
+} Student; 
+
+void print_students(Student stu)
+{
+    printf("%s\t%d\t%d\t%c\t%.2f\n", 
+        stu.name, stu.id, stu.age, stu.group, stu.score);
+}
+
+int main()
+{
+    Student cls[] = {
+        {"张三", 1001, 16, 'A', 95.50},
+        {"李四", 1002, 15, 'A', 90.00},
+        {"王五", 1003, 16, 'B', 80.50}
+    };
+
+    size_t i, num_stu = sizeof(cls) / sizeof(Student);
+    float total = 0, average = 0;
+    printf("=============== 学生基本信息 ===============\n");
+    printf("姓名\t学号\t年龄\t小组\t成绩\n");
+    printf("--------------------------------------------\n");
+    for (i = 0; i < num_stu; ++i) {
+        print_students(cls[i]);
+        total += cls[i].score;
+    }
+    printf("============================================\n");
+    average = total / num_stu;
+    printf("班级平均成绩：%.2f", average);
+
+    return 0;
+}
\ No newline at end of file

data/3.C语言高阶/1.结构体/4.结构体与函数/structures_n_func.json

+{
+    "type": "code_options",
+    "author": "卢昕",
+    "source": "structures_n_func.md",
+    "exercise_id":"d05a0cfc3bd6483b9de9d0c97cc0ace8"
+}
\ No newline at end of file

data/3.C语言高阶/1.结构体/4.结构体与函数/structures_n_func.md

+# 结构体与函数
+
+定义一个学生结构体，并实例化一个结构体数组，用于保存一个班级所有学生的基本信息，最后输出所有学生基本信息，以及班级的学生平均成绩。请选出正确答案。
+
+## 答案
+```c
+#include <stdio.h>
+
+typedef struct
+{
+    char *name;
+    int id;
+    unsigned int age;
+    char group;
+    float score;
+} Student; 
+
+void print_students(Student stu)
+{
+    printf("%s\t%d\t%d\t%c\t%.2f\n", 
+        stu.name, stu.id, stu.age, stu.group, stu.score);
+}
+
+int main()
+{
+    Student cls[] = {
+        {"张三", 1001, 16, 'A', 95.50},
+        {"李四", 1002, 15, 'A', 90.00},
+        {"王五", 1003, 16, 'B', 80.50}
+    };
+
+    size_t i, num_stu = sizeof(cls) / sizeof(Student);
+    float total = 0, average = 0;
+    printf("=============== 学生基本信息 ===============\n");
+    printf("姓名\t学号\t年龄\t小组\t成绩\n");
+    printf("--------------------------------------------\n");
+    for (i = 0; i < num_stu; ++i) {
+        print_students(cls[i]);
+        total += cls[i].score;
+    }
+    printf("============================================\n");
+    average = total / num_stu;
+    printf("班级平均成绩：%.2f", average);
+
+    return 0;
+}
+```
+
+## 选项
+### A
+```c
+#include <stdio.h>
+
+typedef struct
+{
+    char *name;
+    int id;
+    unsigned int age;
+    char group;
+    float score;
+} Student; 
+
+void print_students(Student *stu)
+{
+    printf("%s\t%d\t%d\t%c\t%.2f\n", 
+        stu->name, stu->id, stu->age, stu->group, stu->score);
+}
+
+int main()
+{
+    Student cls[] = {
+        {"张三", 1001, 16, 'A', 95.50},
+        {"李四", 1002, 15, 'A', 90.00},
+        {"王五", 1003, 16, 'B', 80.50}
+    };
+
+    size_t i, num_stu = sizeof(cls) / sizeof(Student);
+    float total = 0, average = 0;
+    printf("=============== 学生基本信息 ===============\n");
+    printf("姓名\t学号\t年龄\t小组\t成绩\n");
+    printf("--------------------------------------------\n");
+    for (i = 0; i < num_stu; ++i) {
+        print_students(cls[i]);
+        total += cls[i].score;
+    }
+    printf("============================================\n");
+    average = total / num_stu;
+    printf("班级平均成绩：%.2f", average);
+
+    return 0;
+}
+```
+
+### B
+```c
+#include <stdio.h>
+
+typedef struct
+{
+    char *name;
+    int id;
+    unsigned int age;
+    char group;
+    float score;
+} Student; 
+
+void print_students(Student *stu)
+{
+    printf("%s\t%d\t%d\t%c\t%.2f\n", 
+        *stu.name, *stu.id, *stu.age, *stu.group, *stu.score);
+}
+
+int main()
+{
+    Student cls[] = {
+        {"张三", 1001, 16, 'A', 95.50},
+        {"李四", 1002, 15, 'A', 90.00},
+        {"王五", 1003, 16, 'B', 80.50}
+    };
+
+    size_t i, num_stu = sizeof(cls) / sizeof(Student);
+    float total = 0, average = 0;
+    printf("=============== 学生基本信息 ===============\n");
+    printf("姓名\t学号\t年龄\t小组\t成绩\n");
+    printf("--------------------------------------------\n");
+    for (i = 0; i < num_stu; ++i) {
+        print_students(&cls[i]);
+        total += cls[i].score;
+    }
+    printf("============================================\n");
+    average = total / num_stu;
+    printf("班级平均成绩：%.2f", average);
+
+    return 0;
+}
+```
+
+### C
+```c
+#include <stdio.h>
+
+typedef struct
+{
+    char *name;
+    int id;
+    unsigned int age;
+    char group;
+    float score;
+} Student; 
+
+void print_students(Student stu)
+{
+    printf("%s\t%d\t%d\t%c\t%.2f\n", 
+        stu->name, stu->id, stu->age, stu->group, stu->score);
+}
+
+int main()
+{
+    Student cls[] = {
+        {"张三", 1001, 16, 'A', 95.50},
+        {"李四", 1002, 15, 'A', 90.00},
+        {"王五", 1003, 16, 'B', 80.50}
+    };
+
+    size_t i, num_stu = sizeof(cls) / sizeof(Student);
+    float total = 0, average = 0;
+    printf("=============== 学生基本信息 ===============\n");
+    printf("姓名\t学号\t年龄\t小组\t成绩\n");
+    printf("--------------------------------------------\n");
+    for (i = 0; i < num_stu; ++i) {
+        print_students(cls[i]);
+        total += cls[i].score;
+    }
+    printf("============================================\n");
+    average = total / num_stu;
+    printf("班级平均成绩：%.2f", average);
+
+    return 0;
+}
+```

data/3.C语言高阶/1.结构体/5.链式结构/config.json

 {
-  "node_id": "569d5e11c4fc5de7844053d9a733c5e8",
-  "keywords": [
-    "结构体",
-    "C语言"
-  ],
-  "children": [],
-  "export": []
+    "node_id": "569d5e11c4fc5de7844053d9a733c5e8",
+    "keywords": [
+        "结构体",
+        "C语言"
+    ],
+    "children": [],
+    "export": [
+        "linked_list.json"
+    ]
 }
\ No newline at end of file

data/3.C语言高阶/1.结构体/5.链式结构/linked_list.c

+#include <stdio.h>
+#include <stdlib.h>
+
+typedef struct Student
+{
+    char *name;
+    int id;
+    unsigned int age;
+    char group;
+    float score;
+    struct Student *next;
+} Student, *Class;
+
+Class init_class()
+{
+    Class head;
+    head = (Student *)malloc(sizeof(Student));
+    if (!head)
+        return NULL;
+    head->next = NULL;
+    return head;
+}
+
+void insert_student(Class cls, char *name, int id, unsigned int age, char group, float score)
+{
+    Class p;
+    p = (Student *)malloc(sizeof(Student));
+    p->name = name, p->id = id, p->age = age, p->group = group, p->score = score;
+    p->next = cls->next;
+    cls->next = p;
+}
+
+void print_class(const Class cls)
+{
+    Class prt = NULL;
+    float total = 0, average = 0;
+    int num_stu = 0;
+    printf("=============== 学生基本信息 ===============\n");
+    printf("姓名\t学号\t年龄\t小组\t成绩\n");
+    printf("--------------------------------------------\n");
+    for (prt = cls->next; prt; prt = prt->next)
+    {
+        printf("%s\t%d\t%d\t%c\t%.2f\n",
+               prt->name, prt->id, prt->age, prt->group, prt->score);
+        total += prt->score;
+        ++num_stu;
+    }
+    printf("============================================\n");
+    average = total / num_stu;
+    printf("班级平均成绩：%.2f", average);
+}
+
+int main()
+{
+    Class cls = init_class();
+    insert_student(cls, "王五", 1003, 16, 'B', 80.50);
+    insert_student(cls, "李四", 1002, 15, 'A', 90.00);
+    insert_student(cls, "张三", 1001, 16, 'A', 95.50);
+
+    print_class(cls);
+
+    return 0;
+}
\ No newline at end of file

data/3.C语言高阶/1.结构体/5.链式结构/linked_list.json

+{
+    "type": "code_options",
+    "author": "卢昕",
+    "source": "linked_list.md",
+    "exercise_id":"af79a964ebfa4116a79cd623357bee1d"
+}
\ No newline at end of file

data/3.C语言高阶/1.结构体/5.链式结构/linked_list.md

+# 链式结构
+
+定义一个学生结构体，并创建一个链表用于保存一个班级所有学生的基本信息，最后输出所有学生基本信息，以及班级的学生平均成绩。请选出正确答案。
+
+## 答案
+```c
+#include <stdio.h>
+#include <stdlib.h>
+
+typedef struct Student
+{
+    char *name;
+    int id;
+    unsigned int age;
+    char group;
+    float score;
+    struct Student *next;
+} Student, *Class;
+
+Class init_class()
+{
+    Class head;
+    head = (Student *)malloc(sizeof(Student));
+    if (!head)
+        return NULL;
+    head->next = NULL;
+    return head;
+}
+
+void insert_student(Class cls, char *name, int id, unsigned int age, char group, float score)
+{
+    Class p;
+    p = (Student *)malloc(sizeof(Student));
+    p->name = name, p->id = id, p->age = age, p->group = group, p->score = score;
+    p->next = cls->next;
+    cls->next = p;
+}
+
+void print_class(const Class cls)
+{
+    Class prt = NULL;
+    float total = 0, average = 0;
+    int num_stu = 0;
+    printf("=============== 学生基本信息 ===============\n");
+    printf("姓名\t学号\t年龄\t小组\t成绩\n");
+    printf("--------------------------------------------\n");
+    for (prt = cls->next; prt; prt = prt->next)
+    {
+        printf("%s\t%d\t%d\t%c\t%.2f\n",
+               prt->name, prt->id, prt->age, prt->group, prt->score);
+        total += prt->score;
+        ++num_stu;
+    }
+    printf("============================================\n");
+    average = total / num_stu;
+    printf("班级平均成绩：%.2f", average);
+}
+
+int main()
+{
+    Class cls = init_class();
+    insert_student(cls, "王五", 1003, 16, 'B', 80.50);
+    insert_student(cls, "李四", 1002, 15, 'A', 90.00);
+    insert_student(cls, "张三", 1001, 16, 'A', 95.50);
+
+    print_class(cls);
+
+    return 0;
+}
+```
+
+## 选项
+### A
+```c
+#include <stdio.h>
+#include <stdlib.h>
+
+typedef struct Student
+{
+    char *name;
+    int id;
+    unsigned int age;
+    char group;
+    float score;
+    struct Student *next;
+} Student, *Class;
+
+Class init_class()
+{
+    Class head;
+    head = (Student *)malloc(sizeof(Student));
+    if (!head)
+        return NULL;
+    head->next = NULL;
+    return head;
+}
+
+void insert_student(Class cls, char *name, int id, unsigned int age, char group, float score)
+{
+    Class p;
+    p = (Student *)malloc(sizeof(Student));
+    p->name = name, p->id = id, p->age = age, p->group = group, p->score = score;
+    p->next = cls->next;
+    cls->next = p;
+}
+
+void print_class(const Class cls)
+{
+    Class prt = NULL;
+    float total = 0, average = 0;
+    int num_stu = 0;
+    printf("=============== 学生基本信息 ===============\n");
+    printf("姓名\t学号\t年龄\t小组\t成绩\n");
+    printf("--------------------------------------------\n");
+    for (prt = cls; prt; prt = prt->next)
+    {
+        printf("%s\t%d\t%d\t%c\t%.2f\n",
+               prt->name, prt->id, prt->age, prt->group, prt->score);
+        total += prt->score;
+        ++num_stu;
+    }
+    printf("============================================\n");
+    average = total / num_stu;
+    printf("班级平均成绩：%.2f", average);
+}
+
+int main()
+{
+    Class cls = init_class();
+    insert_student(cls, "王五", 1003, 16, 'B', 80.50);
+    insert_student(cls, "李四", 1002, 15, 'A', 90.00);
+    insert_student(cls, "张三", 1001, 16, 'A', 95.50);
+
+    print_class(cls);
+
+    return 0;
+}
+```
+
+### B
+```c
+#include <stdio.h>
+#include <stdlib.h>
+
+typedef struct Student
+{
+    char *name;
+    int id;
+    unsigned int age;
+    char group;
+    float score;
+    struct Student *next;
+} Student, *Class;
+
+Class init_class()
+{
+    Class head;
+    head = (Student *)malloc(sizeof(Student));
+    if (!head)
+        return NULL;
+    head->next = NULL;
+    return head;
+}
+
+void insert_student(Class cls, char *name, int id, unsigned int age, char group, float score)
+{
+    Class p, q;
+    p = (Student *)malloc(sizeof(Student));
+    p->name = name, p->id = id, p->age = age, p->group = group, p->score = score;
+    cls->next = p;
+    p->next = cls->next;
+}
+
+void print_class(const Class cls)
+{
+    Class prt = NULL;
+    float total = 0, average = 0;
+    int num_stu = 0;
+    printf("=============== 学生基本信息 ===============\n");
+    printf("姓名\t学号\t年龄\t小组\t成绩\n");
+    printf("--------------------------------------------\n");
+    for (prt = cls->next; prt; prt = prt->next)
+    {
+        printf("%s\t%d\t%d\t%c\t%.2f\n",
+               prt->name, prt->id, prt->age, prt->group, prt->score);
+        total += prt->score;
+        ++num_stu;
+    }
+    printf("============================================\n");
+    average = total / num_stu;
+    printf("班级平均成绩：%.2f", average);
+}
+
+int main()
+{
+    Class cls = init_class();
+    insert_student(cls, "王五", 1003, 16, 'B', 80.50);
+    insert_student(cls, "李四", 1002, 15, 'A', 90.00);
+    insert_student(cls, "张三", 1001, 16, 'A', 95.50);
+
+    print_class(cls);
+
+    return 0;
+}
+```
+
+### C
+```c
+#include <stdio.h>
+#include <stdlib.h>
+
+typedef struct Student
+{
+    char *name;
+    int id;
+    unsigned int age;
+    char group;
+    float score;
+    struct Student *next;
+} Student, *Class;
+
+Class init_class()
+{
+    Class head;
+    head = (Student *)malloc(sizeof(Student));
+    if (!head)
+        return NULL;
+    head->next = NULL;
+    return head;
+}
+
+void insert_student(Class cls, char *name, int id, unsigned int age, char group, float score)
+{
+    Class p;
+    p = (Student *)malloc(sizeof(Student));
+    p->name = name, p->id = id, p->age = age, p->group = group, p->score = score;
+    p->next = cls->next;
+    cls->next = p;
+}
+
+void print_class(const Class cls)
+{
+    Class prt = NULL;
+    float total = 0, average = 0;
+    int num_stu = 0;
+    printf("=============== 学生基本信息 ===============\n");
+    printf("姓名\t学号\t年龄\t小组\t成绩\n");
+    printf("--------------------------------------------\n");
+    for (prt = (*cls).next; prt; ++prt)
+    {
+        printf("%s\t%d\t%d\t%c\t%.2f\n",
+               prt->name, prt->id, prt->age, prt->group, prt->score);
+        total += prt->score;
+        ++num_stu;
+    }
+    printf("============================================\n");
+    average = total / num_stu;
+    printf("班级平均成绩：%.2f", average);
+}
+
+int main()
+{
+    Class cls = init_class();
+    insert_student(cls, "王五", 1003, 16, 'B', 80.50);
+    insert_student(cls, "李四", 1002, 15, 'A', 90.00);
+    insert_student(cls, "张三", 1001, 16, 'A', 95.50);
+
+    print_class(cls);
+
+    return 0;
+}
+```

data/3.C语言高阶/2.联合体/config.json

-{
-  "node_id": "569d5e11c4fc5de7844053d9a733c5e8",
-  "keywords": [
-    "结构体",
-    "C语言"
-  ],
-  "children": [],
-  "export": []
-}
\ No newline at end of file

data/3.C语言高阶/2.联合体与枚举类型/1.联合体/config.json

+{
+    "node_id": "569d5e11c4fc5de7844053d9a733c5e8",
+    "keywords": [
+        "联合体",
+        "共用体"
+    ],
+    "children": [],
+    "export": [
+      "unions.json"
+    ]
+  }
\ No newline at end of file

data/3.C语言高阶/2.联合体与枚举类型/1.联合体/unions.c

+#include <stdio.h>
+#include <string.h>
+#define STR_LEN 20
+
+typedef struct
+{
+    char *name;
+    int id;
+    unsigned int age;
+    char profession[STR_LEN];
+    union
+    {
+        float score;
+        char course[STR_LEN];
+    }un;
+}Person;
+
+int main()
+{
+    Person persons[] = {
+        {.name = "张三", .id = 1001, .age = 16, .profession = "学生", .un.score = 95.50},
+        {.name = "李四", .id = 1002, .age = 15, .profession = "学生", .un.score = 90.00},
+        {.name = "王五", .id = 2001, .age = 26, .profession = "教师", .un.course = "语文"}
+    };
+
+    size_t i, num_per = sizeof(persons) / sizeof(Person);
+    printf("=============== 学生基本信息 ===============\n");
+    printf("姓名\t学号/工号\t年龄\t身份\t成绩/学科\n");
+    printf("--------------------------------------------\n");
+    for (i = 0; i < num_per; ++i) {
+        Person per = persons[i];
+        if (strcmp(per.profession, "学生") == 0)
+            printf("%s\t%d\t\t%d\t%s\t%.2f\n",
+                per.name, per.id, per.age, per.profession, per.un.score);
+        else
+            printf("%s\t%d\t\t%d\t%s\t%s\n",
+                per.name, per.id, per.age, per.profession, per.un.course);
+    }
+    printf("============================================\n");
+
+    return 0;
+}
\ No newline at end of file

data/3.C语言高阶/2.联合体与枚举类型/1.联合体/unions.json

+{
+    "type": "code_options",
+    "author": "卢昕",
+    "source": "unions.md",
+    "exercise_id":"73886fb5ce5c4b1e9db67223b260ee72"
+}
\ No newline at end of file

data/3.C语言高阶/2.联合体与枚举类型/1.联合体/unions.md

+# 联合体
+
+定义一个师生信息结构体，并实例化一个结构体数组，用于保存师生的基本信息，其中 **un** 字段用于保存学生的成绩或者教师的教学科目，最后输出所有人员信息。请选出正确答案。
+
+## 答案
+```c
+#include <stdio.h>
+#include <string.h>
+#define STR_LEN 20
+
+typedef struct
+{
+    char *name;
+    int id;
+    unsigned int age;
+    char profession[STR_LEN];
+    union
+    {
+        float score;
+        char course[STR_LEN];
+    }un;
+}Person;
+
+int main()
+{
+    Person persons[] = {
+        {.name = "张三", .id = 1001, .age = 16, .profession = "学生", .un.score = 95.50},
+        {.name = "李四", .id = 1002, .age = 15, .profession = "学生", .un.score = 90.00},
+        {.name = "王五", .id = 2001, .age = 26, .profession = "教师", .un.course = "语文"}
+    };
+
+    size_t i, num_per = sizeof(persons) / sizeof(Person);
+    printf("=============== 学生基本信息 ===============\n");
+    printf("姓名\t学号/工号\t年龄\t身份\t成绩/学科\n");
+    printf("--------------------------------------------\n");
+    for (i = 0; i < num_per; ++i) {
+        Person per = persons[i];
+        if (strcmp(per.profession, "学生") == 0)
+            printf("%s\t%d\t\t%d\t%s\t%.2f\n",
+                per.name, per.id, per.age, per.profession, per.un.score);
+        else
+            printf("%s\t%d\t\t%d\t%s\t%s\n",
+                per.name, per.id, per.age, per.profession, per.un.course);
+    }
+    printf("============================================\n");
+
+    return 0;
+}
+```
+
+## 选项
+### A
+```c
+#include <stdio.h>
+#include <string.h>
+#define STR_LEN 20
+
+typedef struct
+{
+    char *name;
+    int id;
+    unsigned int age;
+    char profession[STR_LEN];
+    union
+    {
+        float score;
+        char course[STR_LEN];
+    }un;
+}Person;
+
+int main()
+{
+    Person persons[] = {
+        {.name = "张三", .id = 1001, .age = 16, .profession = "学生", .un.score = 95.50},
+        {.name = "李四", .id = 1002, .age = 15, .profession = "学生", .un.score = 90.00},
+        {.name = "王五", .id = 2001, .age = 26, .profession = "教师", .un.course = "语文"}
+    };
+
+    size_t i, num_per = sizeof(persons) / sizeof(Person);
+    printf("=============== 学生基本信息 ===============\n");
+    printf("姓名\t学号/工号\t年龄\t身份\t成绩/学科\n");
+    printf("--------------------------------------------\n");
+    for (i = 0; i < num_per; ++i) {
+        Person per = persons[i];
+        printf("%s\t%d\t\t%d\t%s\t%.2f\n",
+            per.name, per.id, per.age, per.profession, per.un.score);
+    }
+    printf("============================================\n");
+
+    return 0;
+}
+```
+
+### B
+```c
+#include <stdio.h>
+#include <string.h>
+#define STR_LEN 20
+
+typedef struct
+{
+    char *name;
+    int id;
+    unsigned int age;
+    char profession[STR_LEN];
+    union
+    {
+        float score;
+        char course[STR_LEN];
+    }un;
+}Person;
+
+int main()
+{
+    Person persons[] = {
+        {"张三", 1001, 16, "学生", 95.50},
+        {"李四", 1002, 15, "学生", 90.00},
+        {"王五", 2001, 26, "教师", "语文"}
+    };
+
+    size_t i, num_per = sizeof(persons) / sizeof(Person);
+    printf("=============== 学生基本信息 ===============\n");
+    printf("姓名\t学号/工号\t年龄\t身份\t成绩/学科\n");
+    printf("--------------------------------------------\n");
+    for (i = 0; i < num_per; ++i) {
+        Person per = persons[i];
+        if (strcmp(per.profession, "学生") == 0)
+            printf("%s\t%d\t\t%d\t%s\t%.2f\n",
+                per.name, per.id, per.age, per.profession, per.un.score);
+        else
+            printf("%s\t%d\t\t%d\t%s\t%s\n",
+                per.name, per.id, per.age, per.profession, per.un.course);
+    }
+    printf("============================================\n");
+
+    return 0;
+}
+```
+
+### C
+```c
+#include <stdio.h>
+#include <string.h>
+#define STR_LEN 20
+
+typedef struct
+{
+    char *name;
+    int id;
+    unsigned int age;
+    char profession[STR_LEN];
+    union un
+    {
+        float score;
+        char course[STR_LEN];
+    };
+}Person;
+
+int main()
+{
+    Person persons[] = {
+        {.name = "张三", .id = 1001, .age = 16, .profession = "学生", .un.score = 95.50},
+        {.name = "李四", .id = 1002, .age = 15, .profession = "学生", .un.score = 90.00},
+        {.name = "王五", .id = 2001, .age = 26, .profession = "教师", .un.course = "语文"}
+    };
+
+    size_t i, num_per = sizeof(persons) / sizeof(Person);
+    printf("=============== 学生基本信息 ===============\n");
+    printf("姓名\t学号/工号\t年龄\t身份\t成绩/学科\n");
+    printf("--------------------------------------------\n");
+    for (i = 0; i < num_per; ++i) {
+        Person per = persons[i];
+        if (strcmp(per.profession, "学生") == 0)
+            printf("%s\t%d\t\t%d\t%s\t%.2f\n",
+                per.name, per.id, per.age, per.profession, per.un.score);
+        else
+            printf("%s\t%d\t\t%d\t%s\t%s\n",
+                per.name, per.id, per.age, per.profession, per.un.course);
+    }
+    printf("============================================\n");
+
+    return 0;
+}
+```

data/3.C语言高阶/2.联合体与枚举类型/2.枚举类型/config.json

+{
+    "node_id": "569d5e11c4fc5de7844053d9a733c5e8",
+    "keywords": [
+        "枚举",
+        "枚举类型"
+    ],
+    "children": [],
+    "export": [
+        "enum.json"
+    ]
+}
\ No newline at end of file

data/3.C语言高阶/2.联合体与枚举类型/2.枚举类型/enum.c

+#include <stdio.h>
+
+enum week {Mon, Tues, Wed, Thurs, Fri, Sat, Sun};
+enum week dw;
+
+int cal_day_of_week(int y, int m, int d)
+{
+    int dw;
+    if (m == 1 || m == 2)
+    {
+        m += 12;
+        y--;
+    }
+    dw = (d + 2 * m + 3 * (m + 1) / 5 + y + y / 4 - y / 100 + y / 400) % 7;
+    return dw;
+}
+
+int main()
+{
+    int year, month, day;
+    printf("请输入日期(年-月-日)：\n");
+    scanf("%d-%d-%d", &year, &month, &day);
+    dw = cal_day_of_week(year, month, day);
+    switch (dw)
+    {
+        case week.Mon: printf("星期一\n"); break;
+        case week.Tues: printf("星期二\n"); break;
+        case week.Wed: printf("星期三\n"); break;
+        case week.Thurs: printf("星期四\n"); break;
+        case week.Fri: printf("星期五\n"); break;
+        case week.Sat: printf("星期六\n"); break;
+        case week.Sun: printf("星期日\n"); break;
+    }
+
+    return 0;
+}

data/3.C语言高阶/2.联合体与枚举类型/2.枚举类型/enum.json

+{
+    "type": "code_options",
+    "author": "卢昕",
+    "source": "enum.md",
+    "exercise_id":"44888a39b3be432a854447cd603b348e"
+}
\ No newline at end of file

data/3.C语言高阶/2.联合体与枚举类型/2.枚举类型/enum.md

+# 枚举类型
+
+输入一个日期(年月日)，输出该日期是星期几。请选出错误答案。
+
+## 答案
+```c
+#include <stdio.h>
+
+enum week {Mon, Tues, Wed, Thurs, Fri, Sat, Sun};
+enum week dw;
+
+int cal_day_of_week(int y, int m, int d)
+{
+    int dw;
+    if (m == 1 || m == 2)
+    {
+        m += 12;
+        y--;
+    }
+    dw = (d + 2 * m + 3 * (m + 1) / 5 + y + y / 4 - y / 100 + y / 400) % 7;
+    return dw;
+}
+
+int main()
+{
+    int year, month, day;
+    printf("请输入日期(年-月-日)：\n");
+    scanf("%d-%d-%d", &year, &month, &day);
+    dw = cal_day_of_week(year, month, day);
+    switch (dw)
+    {
+        case week.Mon: printf("星期一\n"); break;
+        case week.Tues: printf("星期二\n"); break;
+        case week.Wed: printf("星期三\n"); break;
+        case week.Thurs: printf("星期四\n"); break;
+        case week.Fri: printf("星期五\n"); break;
+        case week.Sat: printf("星期六\n"); break;
+        case week.Sun: printf("星期日\n"); break;
+    }
+
+    return 0;
+}
+```
+
+## 选项
+### A
+```c
+#include <stdio.h>
+
+enum week {Mon, Tues, Wed, Thurs, Fri, Sat, Sun};
+enum week dw;
+
+int cal_day_of_week(int y, int m, int d)
+{
+    int dw;
+    if (m == 1 || m == 2)
+    {
+        m += 12;
+        y--;
+    }
+    dw = (d + 2 * m + 3 * (m + 1) / 5 + y + y / 4 - y / 100 + y / 400) % 7;
+    return dw;
+}
+
+int main()
+{
+    int year, month, day;
+    printf("请输入日期(年-月-日)：\n");
+    scanf("%d-%d-%d", &year, &month, &day);
+    dw = cal_day_of_week(year, month, day);
+    switch (dw)
+    {
+        case Mon: printf("星期一\n"); break;
+        case Tues: printf("星期二\n"); break;
+        case Wed: printf("星期三\n"); break;
+        case Thurs: printf("星期四\n"); break;
+        case Fri: printf("星期五\n"); break;
+        case Sat: printf("星期六\n"); break;
+        case Sun: printf("星期日\n"); break;
+    }
+
+    return 0;
+}
+```
+
+### B
+```c
+#include <stdio.h>
+
+enum week {Mon=0, Tues=1, Wed=2, Thurs=3, Fri=4, Sat=5, Sun=6};
+enum week dw;
+
+int cal_day_of_week(int y, int m, int d)
+{
+    int dw;
+    if (m == 1 || m == 2)
+    {
+        m += 12;
+        y--;
+    }
+    dw = (d + 2 * m + 3 * (m + 1) / 5 + y + y / 4 - y / 100 + y / 400) % 7;
+    return dw;
+}
+
+int main()
+{
+    int year, month, day;
+    printf("请输入日期(年-月-日)：\n");
+    scanf("%d-%d-%d", &year, &month, &day);
+    dw = cal_day_of_week(year, month, day);
+    switch (dw)
+    {
+        case Mon: printf("星期一\n"); break;
+        case Tues: printf("星期二\n"); break;
+        case Wed: printf("星期三\n"); break;
+        case Thurs: printf("星期四\n"); break;
+        case Fri: printf("星期五\n"); break;
+        case Sat: printf("星期六\n"); break;
+        case Sun: printf("星期日\n"); break;
+    }
+
+    return 0;
+}
+
+```
+
+### C
+```c
+#include <stdio.h>
+
+enum week {Mon=0, Tues, Wed, Thurs, Fri, Sat, Sun};
+enum week dw;
+
+int cal_day_of_week(int y, int m, int d)
+{
+    int dw;
+    if (m == 1 || m == 2)
+    {
+        m += 12;
+        y--;
+    }
+    dw = (d + 2 * m + 3 * (m + 1) / 5 + y + y / 4 - y / 100 + y / 400) % 7;
+    return dw;
+}
+
+int main()
+{
+    int year, month, day;
+    printf("请输入日期(年-月-日)：\n");
+    scanf("%d-%d-%d", &year, &month, &day);
+    dw = cal_day_of_week(year, month, day);
+    switch (dw)
+    {
+        case Mon: printf("星期一\n"); break;
+        case Tues: printf("星期二\n"); break;
+        case Wed: printf("星期三\n"); break;
+        case Thurs: printf("星期四\n"); break;
+        case Fri: printf("星期五\n"); break;
+        case Sat: printf("星期六\n"); break;
+        case Sun: printf("星期日\n"); break;
+    }
+
+    return 0;
+}
+
+```

data/3.C语言高阶/2.联合体与枚举类型/config.json

+{
+    "node_id": "569d5e11c4fc5de7844053d9a733c5e8",
+    "keywords": [
+        "联合体",
+        "共用体",
+        "枚举类型",
+        "枚举"
+    ]
+}
\ No newline at end of file