added Esercizi n. 4

Esercizi n. 4/Makefile

+CC = clang
+CFLAGS = -Wall -Wextra -g
+objects = list.o person.o main.o
+
+build: $(objects)
+	$(CC) $(CFLAGS) $(objects) -o main
+list.o: list.c list.h
+	$(CC) -c $(CFLAGS) $< -o $@
+person.o: person.c person.h
+	$(CC) -c $(CFLAGS) $< -o $@
+main.o: main.c
+	$(CC) -c $(CFLAGS) $< -o $@
+clean:
+	rm $(objects) main

Esercizi n. 4/list.c

+#include <stdlib.h>
+#include "list.h"
+
+List node_alloc(void) {
+    return malloc(sizeof(Head));
+}
+
+void list_insert_tail(List *list, Data data) {
+    while (*list) {
+        list = &(*list)->next;
+    }
+    *list = node_alloc();
+    (*list)->data = data;
+    (*list)->next = NULL;
+}
+
+void list_insert_head(List *list, Data data) {
+    List next = *list;
+    *list = node_alloc();
+    (*list)->data = data;
+    (*list)->next = next;
+}
+
+List *list_find_ref(List *list, int (*predicate) (Data *, Data *), Data *key) {
+    if (*list) {
+        return predicate(&(*list)->data, key)
+            ? list
+            : list_find_ref(&(*list)->next, predicate, key);
+    }
+    return NULL;
+}
+
+List list_filter(List list, int (*predicate) (Data *, Data *), Data *key) {
+    if (list) {
+        if (predicate(&list->data, key)) {
+            List new = node_alloc();
+            new->data = list->data;
+            new->next = list_filter(list->next, predicate, key);
+            return new;
+        }
+        return list_filter(list->next, predicate, key);
+    }
+    return NULL;
+}
+
+void list_output(List list, void (*print) (Data *)) {
+    if (list) {
+        print(&list->data);
+        list_output(list->next, print);
+    }
+}

Esercizi n. 4/list.h

+#ifndef LIST_H
+#define LIST_H
+
+#include "person.h"
+
+typedef Person Data;
+
+typedef struct Head {
+    Person data;
+    struct Head *next;
+} Head;
+
+typedef Head *List;
+
+List node_alloc(void);
+void list_insert_tail(List *list, Data data);
+void list_insert_head(List *list, Data data);
+List list_filter(List list, int (*predicate) (Data *, Data *), Data *key);
+List *list_find_ref(List *list, int (*predicate) (Data *, Data *), Data *key);
+void list_output(List list, void (*print) (Data *));
+
+#endif

Esercizi n. 4/main.c

+#include <stdio.h>
+#include "person.h"
+#include "list.h"
+
+int person_is_minor_adj(Person *person, Person *_) {
+    (void)_;
+    return person_is_minor(person);
+}
+
+int person_is_adult_adj(Person *person, Person *_) {
+    (void)_;
+    return !person_is_minor_adj(person, NULL);
+}
+
+void insert(List *list) {
+    Person person;
+    puts("inserire persona");
+    person_input(&person);
+
+    int (*predicate) (Person *, Person *) = person_is_minor(&person)
+        ? person_is_minor_adj
+        : person_is_adult_adj;
+    List *found;
+    if ((found = list_find_ref(list, predicate, NULL))) {
+        List next = *found;
+        *found = node_alloc();
+        (*found)->data = person;
+        (*found)->next = next;
+    } else {
+        list_insert_head(list, person);
+    }
+}
+
+List filter_relatives(List list, Person *relative) {
+    return list_filter(list, person_is_relative, relative);
+}
+
+int main(void) {
+    List list = NULL;
+
+    Person tmp;
+    puts("persona da inserire in fondo");
+    person_input(&tmp);
+    list_insert_tail(&list, tmp);
+
+    list_output(list, person_output);
+    
+    puts("persona da inserire in testa");
+    person_input(&tmp);
+    list_insert_head(&list, tmp);
+
+    insert(&list);
+
+    list_output(list, person_output);
+
+    puts("persona parente");
+    person_input(&tmp);
+    List relatives = filter_relatives(list, &tmp);
+    puts("parenti");
+    list_output(relatives, person_output);
+}

Esercizi n. 4/person.c

+#include "person.h"
+#include <string.h>
+#include <stdio.h>
+
+void person_input(Person *person) {
+    scanf(
+        "%63s %63s %u",
+        person->first_name,
+        person->last_name,
+        &person->age
+    );
+}
+
+int person_is_relative(Person *p1, Person *p2) {
+    return strcmp(p1->last_name, p2->last_name) == 0;
+}
+
+void person_output(Person *person) {
+    printf(
+        "nome: %s, cognome: %s, anni: %u\n",
+        person->first_name,
+        person->last_name,
+        person->age
+    );
+}
+
+int person_is_minor(Person *person) {
+    return person->age < 18;
+}

Esercizi n. 4/person.h

+#ifndef PERSON_H
+#define PERSON_H
+
+typedef struct {
+    char first_name[64];
+    char last_name[64];
+    unsigned int age;
+} Person;
+
+void person_input(Person *person);
+int person_is_relative(Person *p1, Person *p2);
+void person_output(Person *person);
+int person_is_minor(Person *person);
+
+#endif