added todays exercise 7, 8, 9

Lezione 5/7/input.txt

+Mario Rossi 0
+Giuseppe Verdi 0
+Luigi Rossi 0
+Andrea Neri 0
+Alessia Rossi 0
+Simone Rossi 0
+END

Lezione 5/7/main.c

+#include <assert.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#define ARR_LEN(arr) (sizeof(arr) / sizeof(*arr))
+#define FILE_END "END" 
+
+typedef struct {
+    char first_name[64];
+    char last_name[64];
+    unsigned int age;
+} Person;
+
+char *fgets_strip(char *s, int size, FILE *stream) {
+    char *ret = fgets(s, size, stream);
+    s[strcspn(s, "\n")] = 0;
+    return ret;
+}
+
+int person_parse(char *s, Person *person) {
+    char format[4 + 1 + 4 + 1 + 2 + 1];
+    assert((size_t)snprintf(
+        format,
+        ARR_LEN(format),
+        "%%%zus %%%zus %%u",
+        ARR_LEN(person->first_name),
+        ARR_LEN(person->last_name)
+    ) < ARR_LEN(format));
+
+    return sscanf(
+        s,
+        format,
+        person->first_name,
+        person->last_name,
+        &person->age
+    ) < 3 ? -1 : 0;
+}
+
+int person_read(FILE *f, Person *person) {
+    char buf[256];
+    fgets_strip(buf, ARR_LEN(buf), f);
+
+    if (strncmp(buf, FILE_END, ARR_LEN(FILE_END)) == 0) {
+        return 0;
+    }
+    return person_parse(buf, person) < 0 ? 0 : 1;
+}
+
+void person_print(Person *person) {
+    printf(
+        "nome: %s, cognome: %s, eta': %u\n",
+        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;
+}
+
+typedef Person Data;
+
+typedef struct ListHead {
+    struct ListHead *next;
+    Data data;
+} ListHead;
+
+typedef ListHead *Link;
+
+Link list_new_raw(void) {
+    return malloc(sizeof(ListHead));
+}
+
+Link list_new(Data data) {
+    Link ret = list_new_raw();
+    ret->data = data;
+    ret->next = NULL;
+    return ret;
+}
+
+Link list_input(FILE *f, int (*input) (FILE *, Data *)) {
+    ListHead *head = NULL;
+    ListHead **next = &head;
+
+    Data data;
+    while (input(f, &data)) {
+        *next = list_new(data);
+        next = &(*next)->next;
+    }
+    return head;
+}
+
+Link list_find(Link head, Data *key, int (*compare) (Data *, Data *)) {
+    while (head && !compare(key, &head->data)) {
+        head = head->next;
+    }
+    return head;
+}
+
+Link list_find_nth(Link head, Data *key, size_t n, int (*compare) (Data *, Data *)) {
+    size_t count = 0;
+    Link found;
+    while (count < n && (found = list_find(head, key, compare))) {
+        ++count;
+        head = found->next;
+    }
+    return found;
+}
+
+int main(void) {
+    FILE *f = fopen("input.txt", "r");
+    Link list = list_input(f, person_read);
+    fclose(f);
+
+    Person key;
+    puts("inserire cognome");
+    fgets_strip(key.last_name, ARR_LEN(key.last_name), stdin);
+
+    puts("inserire n");
+    size_t n;
+    scanf("%zu", &n);
+
+    Link found = list_find_nth(list, &key, n, person_is_relative);
+    if (found) {
+        person_print(&found->data);
+    } else {
+        puts("il parente ricercato non esiste");
+    }
+}

Lezione 5/8/input.txt

+Mario Rossi 12
+Giuseppe Verdi 0
+Luigi Rossi 14
+Andrea Neri 0
+Alessia Rossi 20
+Simone Rossi 20
+END

Lezione 5/8/main.c

+#include <assert.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#define ARR_LEN(arr) (sizeof(arr) / sizeof(*arr))
+#define FILE_END "END" 
+
+typedef struct {
+    char first_name[64];
+    char last_name[64];
+    unsigned int age;
+} Person;
+
+char *fgets_strip(char *s, int size, FILE *stream) {
+    char *ret = fgets(s, size, stream);
+    s[strcspn(s, "\n")] = 0;
+    return ret;
+}
+
+int person_parse(char *s, Person *person) {
+    char format[4 + 1 + 4 + 1 + 2 + 1];
+    assert((size_t)snprintf(
+        format,
+        ARR_LEN(format),
+        "%%%zus %%%zus %%u",
+        ARR_LEN(person->first_name),
+        ARR_LEN(person->last_name)
+    ) < ARR_LEN(format));
+
+    return sscanf(
+        s,
+        format,
+        person->first_name,
+        person->last_name,
+        &person->age
+    ) < 3 ? -1 : 0;
+}
+
+int person_read(FILE *f, Person *person) {
+    char buf[256];
+    fgets_strip(buf, ARR_LEN(buf), f);
+
+    if (strncmp(buf, FILE_END, ARR_LEN(FILE_END)) == 0) {
+        return 0;
+    }
+    return person_parse(buf, person) < 0 ? 0 : 1;
+}
+
+void person_print(Person *person) {
+    printf(
+        "nome: %s, cognome: %s, eta': %u\n",
+        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;
+}
+
+int person_is_adult(Person *p1) {
+    return p1->age >= 18;
+}
+
+int person_is_relative_adult(Person *p1, Person *p2) {
+    return person_is_relative(p1, p2) && person_is_adult(p1);
+}
+
+typedef Person Data;
+
+typedef struct ListHead {
+    struct ListHead *next;
+    Data data;
+} ListHead;
+
+typedef ListHead *Link;
+
+Link list_new_raw(void) {
+    return malloc(sizeof(ListHead));
+}
+
+Link list_new(Data data) {
+    Link ret = list_new_raw();
+    ret->data = data;
+    ret->next = NULL;
+    return ret;
+}
+
+Link list_input(FILE *f, int (*input) (FILE *, Data *)) {
+    ListHead *head = NULL;
+    ListHead **next = &head;
+
+    Data data;
+    while (input(f, &data)) {
+        *next = list_new(data);
+        next = &(*next)->next;
+    }
+    return head;
+}
+
+Link list_find(Link head, Data *key, int (*compare) (Data *, Data *)) {
+    while (head && !compare(key, &head->data)) {
+        head = head->next;
+    }
+    return head;
+}
+
+Link list_find_last(Link head, Data *key, int (*compare) (Data *, Data *)) {
+    Link found = head;
+    Link previous = NULL;
+    while ((found = list_find(found, key, compare))) {
+        previous = found;
+        found = found->next;
+    }
+    return previous;
+}
+
+int main(void) {
+    FILE *f = fopen("input.txt", "r");
+    Link list = list_input(f, person_read);
+    fclose(f);
+
+    Person key;
+    puts("inserire cognome");
+    fgets_strip(key.last_name, ARR_LEN(key.last_name), stdin);
+
+    Link found = list_find_last(list, &key, person_is_relative_adult);
+    if (found) {
+        person_print(&found->data);
+    } else {
+        puts("il parente ricercato non esiste");
+    }
+}

Lezione 5/9/input.txt

+Mario Rossi 12
+Giuseppe Verdi 18
+Luigi Rossi 14
+Andrea Neri 11
+Alessia Rossi 20
+Simone Rossi 20
+END

Lezione 5/9/main.c

+#include <assert.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#define ARR_LEN(arr) (sizeof(arr) / sizeof(*arr))
+#define FILE_END "END" 
+
+typedef struct {
+    char first_name[64];
+    char last_name[64];
+    unsigned int age;
+} Person;
+
+char *fgets_strip(char *s, int size, FILE *stream) {
+    char *ret = fgets(s, size, stream);
+    s[strcspn(s, "\n")] = 0;
+    return ret;
+}
+
+int person_parse(char *s, Person *person) {
+    char format[4 + 1 + 4 + 1 + 2 + 1];
+    assert((size_t)snprintf(
+        format,
+        ARR_LEN(format),
+        "%%%zus %%%zus %%u",
+        ARR_LEN(person->first_name),
+        ARR_LEN(person->last_name)
+    ) < ARR_LEN(format));
+
+    return sscanf(
+        s,
+        format,
+        person->first_name,
+        person->last_name,
+        &person->age
+    ) < 3 ? -1 : 0;
+}
+
+int person_read(FILE *f, Person *person) {
+    char buf[256];
+    fgets_strip(buf, ARR_LEN(buf), f);
+
+    if (strncmp(buf, FILE_END, ARR_LEN(FILE_END)) == 0) {
+        return 0;
+    }
+    return person_parse(buf, person) < 0 ? 0 : 1;
+}
+
+void person_print(Person *person) {
+    printf(
+        "nome: %s, cognome: %s, eta': %u\n",
+        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;
+}
+
+int person_is_adult(Person *p1, Person *_) {
+    (void)_;
+    return p1->age >= 18;
+}
+
+int person_is_underage(Person *p1, Person *p2) {
+    return !person_is_adult(p1, p2);
+}
+
+unsigned int person_add_age(unsigned int to_add, Person *p) {
+    return p->age + to_add;
+}
+
+typedef Person Data;
+
+typedef struct ListHead {
+    struct ListHead *next;
+    Data data;
+} ListHead;
+
+typedef ListHead *Link;
+
+Link list_new_raw(void) {
+    return malloc(sizeof(ListHead));
+}
+
+Link list_new(Data data) {
+    Link ret = list_new_raw();
+    ret->data = data;
+    ret->next = NULL;
+    return ret;
+}
+
+Link list_input(FILE *f, int (*input) (FILE *, Data *)) {
+    ListHead *head = NULL;
+    ListHead **next = &head;
+
+    Data data;
+    while (input(f, &data)) {
+        *next = list_new(data);
+        next = &(*next)->next;
+    }
+    return head;
+}
+
+Link list_find(Link head, Data *key, int (*compare) (Data *, Data *)) {
+    while (head && !compare(&head->data, key)) {
+        head = head->next;
+    }
+    return head;
+}
+
+unsigned int list_filter_fold(
+    Link head,
+    Data *key,
+    int (*compare) (Data *, Data *),
+    unsigned int init,
+    unsigned int (*op) (unsigned int, Data *))
+{
+    Link found = head;
+    unsigned int accumulator = init;
+    while ((found = list_find(found, key, compare))) {
+        accumulator = op(accumulator, &found->data);
+        found = found->next;
+    }
+    return accumulator;
+}
+
+int main(void) {
+    FILE *f = fopen("input.txt", "r");
+    Link list = list_input(f, person_read);
+    fclose(f);
+
+    unsigned int sum_underage = list_filter_fold(
+        list,
+        NULL,
+        person_is_underage,
+        0,
+        person_add_age
+    );
+    printf("somma eta' minorenni: %u\n", sum_underage);
+
+    unsigned int sum_adults = list_filter_fold(
+        list,
+        NULL,
+        person_is_adult,
+        0,
+        person_add_age
+    );
+    printf("somma eta' maggiorenni: %u\n", sum_adults);
+
+    Person key;
+    puts("inserire cognome");
+    fgets_strip(key.last_name, ARR_LEN(key.last_name), stdin);
+    unsigned int sum_relatives = list_filter_fold(
+        list,
+        &key,
+        person_is_relative,
+        0,
+        person_add_age
+    );
+    printf("somma eta' %s: %u\n", key.last_name, sum_relatives);
+}