C: تطبيق： الأنواع المخصصة

typedef struct {
    char name[32];
    char id[16];
    int chinese;
    int math;
    int english;
} Student;

typedef struct {
    Student *data;
    int count;
    int capacity;
} StudentList;

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

typedef struct {
    char name[32];
    char id[16];
    int chinese;
    int math;
    int english;
} Student;

typedef struct {
    Student *data;
    int count;
    int capacity;
} StudentList;

void list_init(StudentList *list) {
    list->capacity = 4;
    list->count = 0;
    list->data = (Student *)malloc(sizeof(Student) * list->capacity);
}

void list_free(StudentList *list) {
    free(list->data);
    list->data = NULL;
    list->count = 0;
    list->capacity = 0;
}

void list_expand(StudentList *list) {
    if (list->count < list->capacity) return;
    list->capacity *= 2;
    Student *tmp = (Student *)realloc(list->data, sizeof(Student) * list->capacity);
    if (tmp) list->data = tmp;
}

void list_add(StudentList *list, const Student *s) {
    list_expand(list);
    list->data[list->count++] = *s;
}

int total_score(const Student *s) {
    return s->chinese + s->math + s->english;
}

double avg_score(const Student *s) {
    return total_score(s) / 3.0;
}

Student *find_by_id(StudentList *list, const char *id) {
    for (int i = 0; i < list->count; i++) {
        if (strcmp(list->data[i].id, id) == 0) {
            return &list->data[i];
        }
    }
    return NULL;
}

int cmp_by_total(const void *a, const void *b) {
    int ta = total_score((const Student *)a);
    int tb = total_score((const Student *)b);
    return tb - ta;
}

void sort_by_total(StudentList *list) {
    qsort(list->data, list->count, sizeof(Student), cmp_by_total);
}

int main(void) {
    StudentList list;
    list_init(&list);

    Student s1 = {"001", "Zhang", 85, 92, 78};
    Student s2 = {"002", "Li", 90, 88, 95};
    Student s3 = {"003", "Wang", 72, 65, 80};

    list_add(&list, &s1);
    list_add(&list, &s2);
    list_add(&list, &s3);

    sort_by_total(&list);

    Student *found = find_by_id(&list, "001");
    if (found) {
        printf("Found 001: %s Total=%d\n", found->name, total_score(found));
    }

    list_free(&list);
    return 0;
}

Found 001: Zhang Total=255

typedef struct {
    char name[32];
    char phone[16];
    char email[40];
    char group[16];
} Contact;

typedef struct {
    Contact *data;
    int count;
    int capacity;
} ContactList;

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

typedef struct {
    char name[32];
    char phone[16];
    char email[40];
    char group[16];
} Contact;

typedef struct {
    Contact *data;
    int count;
    int capacity;
} ContactList;

void clist_init(ContactList *list) {
    list->capacity = 4;
    list->count = 0;
    list->data = (Contact *)malloc(sizeof(Contact) * list->capacity);
}

void clist_free(ContactList *list) {
    free(list->data);
    list->data = NULL;
    list->count = 0;
    list->capacity = 0;
}

void clist_expand(ContactList *list) {
    if (list->count < list->capacity) return;
    list->capacity *= 2;
    Contact *tmp = (Contact *)realloc(list->data, sizeof(Contact) * list->capacity);
    if (tmp) list->data = tmp;
}

void clist_add(ContactList *list, const Contact *c) {
    clist_expand(list);
    list->data[list->count++] = *c;
}

int clist_remove(ContactList *list, const char *name) {
    for (int i = 0; i < list->count; i++) {
        if (strcmp(list->data[i].name, name) == 0) {
            list->data[i] = list->data[list->count - 1];
            list->count--;
            return 0;
        }
    }
    return -1;
}

Contact *clist_find(ContactList *list, const char *name) {
    for (int i = 0; i < list->count; i++) {
        if (strcmp(list->data[i].name, name) == 0) {
            return &list->data[i];
        }
    }
    return NULL;
}

int main(void) {
    ContactList list;
    clist_init(&list);

    Contact c1 = {"Zhang", "13800001111", "zhangsan@mail.com", "Coworker"};
    Contact c2 = {"Li", "13900002222", "lisi@mail.com", "Friend"};
    Contact c3 = {"Wang", "15000003333", "wangwu@mail.com", "Coworker"};
    Contact c4 = {"Zhao", "18600004444", "zhaoliu@mail.com", "Family"};

    clist_add(&list, &c1);
    clist_add(&list, &c2);
    clist_add(&list, &c3);
    clist_add(&list, &c4);

    Contact *found = clist_find(&list, "Li");
    if (found) {
        printf("Found Li: %s %s\n", found->phone, found->email);
    }

    clist_remove(&list, "Wang");

    clist_free(&list);
    return 0;
}

Found Li: 13900002222 lisi@mail.com

fprintf(fp, "%d\n", count);
for (int i = 0; i < count; i++) {
    fprintf(fp, "field1 field2 ...\n", ...);
}