C
Putting it together
Combine the library modules with a menu.
Putting it together with a menu
In the final step you combine all modules under a menu. The menu_run(Library *lib, int choice) function acts on choice: 1 lists all books, 2 checks out, 3 searches.
A switch (choice) branches the flow. Each case calls the relevant function. This structure is the skeleton of a real console app. In main we call the menu with fixed choices to test the output; in a real app you'd read the choice with scanf. In this final lesson all pieces come together: model, collection, checkout and search.
menu_run implementation
The void menu_run(Library *lib, int choice) function branches with switch. case 1: loop and print_book for all books. case 2: call checkout(&lib->books[0]). case 3: use find_by_title to search.
In main start with Library lib;, add a book, then call menu_run(&lib, 1);. This runs the menu's listing option. All modules meet here: print_book, library_add, checkout and find_by_title. The five-lesson project is complete; you have the skeleton of a real C console app.
Exercise Integrate with menu_run
Add void menu_run(Library *lib, int choice) to the existing code. With switch (choice) add case 1: for (int i = 0; i < lib->count; i++) print_book(&lib->books[i]); and break;. In main add a book and call menu_run(&lib, 1);.
Show example solution
#include <stdio.h>
#include <string.h>
typedef struct {
char title[64];
int year;
int borrowed;
} Book;
typedef struct {
char name[64];
int id;
} Member;
typedef struct {
Book books[10];
int count;
} Library;
void library_init(Library *lib) {
lib->count = 0;
}
void library_add(Library *lib, Book b) {
lib->books[lib->count++] = b;
}
void print_book(Book *b) {
printf("Book: %s (%d)\n", b->title, b->year);
}
int checkout(Book *b) {
if (b->borrowed) return 0;
b->borrowed = 1;
return 1;
}
int return_book(Book *b) {
if (!b->borrowed) return 0;
b->borrowed = 0;
return 1;
}
Book *find_by_title(Library *lib, const char *title) {
for (int i = 0; i < lib->count; i++) {
if (strcmp(lib->books[i].title, title) == 0) return &lib->books[i];
}
return NULL;
}
void menu_run(Library *lib, int choice) {
switch (choice) {
case 1:
for (int i = 0; i < lib->count; i++) print_book(&lib->books[i]);
break;
}
}
int main(void) {
Library lib;
library_init(&lib);
Book b1 = {"C Tutorial", 2024, 0};
library_add(&lib, b1);
menu_run(&lib, 1);
return 0;
}
Test yourself
-
What does menu option 1 do?
- Checks out
- Exits
- Searches
- Lists books
Show answer
Lists books — Option 1 lists all books via print_book.
-
Complete the switch case
switch (choice) {
case 1:
for (int i = 0; i < lib->count; i++) ____(&lib->books[i]);
break;
}
Show answer
switch (choice) {
case 1:
for (int i = 0; i < lib->count; i++) print_book(&lib->books[i]);
break;
}
-
Match menu options
- case 1
- List books
- case 2
- Check out
- case 3
- Search
- default
- Unknown choice
Next lesson: Linked list
