Important concepts

To study operating system concepts we will use the C programming language. To be able to understand the tutorials and solve the programming assignments you will need to be familiar with the following C programming concepts.

• Basic data types such as int and char.
• Arrays.
• Strings (array of char).
• Basic use of the #define directive.
• Basic use of printf() to print text to the terminal.
• The if-then-else control structure.
• The switch control structure.
• The while loop.
• The for loop.
• Functions and function calls.
• Pointers.
• Structures.
• Pointers to structures.
• Call by reference.
• Dynamic memory allocation (malloc and free).
• Header files.
• Separate compilation.

C learning resources

For the tutorials and programming assignments you will be required to use the C programming language. If you are new to C or need to refresh you knowledge there are plenty of resources available on the web. On this page you find a small collections of recommended links.

A short introduction to C programming

• C Programming Introduction (PDF) is a comprehensive set of slides introducing the basic concepts of C programming put together by Md Tahseen Anam, teaching assistant on the OS (1DT044) course, autumn 2020.

C programming tutorials

• The Basics of C Programming: A very nice online tutorial over the entire C language.
• Online C reference: An easy to navigate reference to the C programming language.
• Online C tutorial:

Pointer fun with Blinky

• Pointer Fun in C wiht Binky (Youtube): Binky talks about pointers, pointees and the dereference operator (magic wand of dereference).
• Reference Fun in Java with Binky (Youtube): The classic Binky video but with code examples in Java.

Online books

• The online C book: This is the online version of The C Book, second edition by Mike Banahan, Declan Brady and Mark Doran, originally published by Addison Wesley in 1991.

C for java programmers

• C and C++ for Java Programmers: If you are familiar with the Java programming language already but are new to the C programming language, this might be for you.
• C for Java Programmers (PDF): This is another introduction to the C programming language for people who already know Java.

C programming exercise

Before starting working on the tutorials and programming assignments you should make sure you are familiar with a few important C programming concepts. To test your C programming skills you are encouraged to solve the programming exercise described below.

Clone repository

Before you continue, you must clone the c-address-book repository. From the terminal, navigate to a directory where you want the cloned directory to be created and execute the following command.

git clone https://github.com/os-assignments/c-address-book.git

address_book.h

The functions you need to implement are already declared in address_book.h. You should also define the structures you will need in address_book.h. You are free to create more functions if you want.

address_book.c

In the file address_book.c you should implement the functions declared in adress_book.h.

main.c

The main() function, which is the entry point of your program will be in a file called main.c.

Representing a person

Create a struct Person that will be used to represent a person. This struct should store:

• The full name
• The age
• The phone number

It is up to you to choose the right datatypes for the fields of the structure.

Representing the address book

Create a struct Address_book that will contain a pointer to an array of struct Person, as well as the size of this array (the number of persons in the address book).

Printing a person

Create a function print_person() that takes a pointer to a Person structure and prints its details on the standard output.

A possible output for a person named John Doe, 42 years old, with the phone number +46712345678:

Name: John Doe
Age: 42
Phone number: +46712345678

Printing an address book

Create a function print_address_book() that takes a pointer to an address book and prints its details on the standard output. Make use of the print_person() function you just created.

A possible output for an address book containing two entries is:

==== Address book (2 entries) =====

Name: John Doe
Age: 42
Phone number: +46712345678

Name: Foo Bar
Age: 24
Phone number: +46787654321

Creating an address book

We will now read information from the user and store it into an address book.

Create a create_address_book() function. This function should:

• Create (dynamically) an empty address book.
• Read from the standard input the number of persons that the user intends to put into the address book.
• Dynamically allocate an array of struct Person of the correct size and store a pointer to it in the address book. You are not allowed to use Variable Length Arrays!
• In a loop, read from the standard input the information you need for every person to be stored in the address book. Assume that the inputs are correct, so you are not expected to validate them.
• Return the address book.

Hints: Dynamic allocation is done with malloc(). Reading from the standard input can be done using scanf() or fgets().