0x19. C - Stacks, Queues - LIFO, FIFO

Resources

Read or watch:

Learning Objectives

At the end of this project, you are expected to be able to explain to anyone, without the help of Google:

General

What do LIFO and FIFO mean
What is a stack, and when to use it
What is a queue, and when to use it
What are the common implementations of stacks and queues
What are the most common use cases of stacks and queues
What is the proper way to use global variables

Copyright - Plagiarism

You are tasked to come up with solutions for the tasks below yourself to meet with the above learning objectives.
You will not be able to meet the objectives of this or any following project by copying and pasting someone else’s work.
You are not allowed to publish any content of this project.
Any form of plagiarism is strictly forbidden and will result in removal from the program.

Requirements

General

Allowed editors: vi, vim, emacs
All your files will be compiled on Ubuntu 20.04 LTS using gcc, using the options -Wall -Werror -Wextra -pedantic -std=c89
All your files should end with a new line
A README.md file, at the root of the folder of the project is mandatory
Your code should use the Betty style. It will be checked using betty-style.pl and betty-doc.pl
You allowed to use a maximum of one global variable
No more than 5 functions per file
You are allowed to use the C standard library
The prototypes of all your functions should be included in your header file called monty.h
Don’t forget to push your header file
All your header files should be include guarded
You are expected to do the tasks in the order shown in the project

GitHub

There should be one project repository per group. If you clone/fork/whatever a project repository with the same name before the second deadline, you risk a 0% score.

More Info

Data structures

Please use the following data structures for this project. Don’t forget to include them in your header file.

    /**
     * struct stack_s - doubly linked list representation of a stack (or queue)
     * @n: integer
     * @prev: points to the previous element of the stack (or queue)
     * @next: points to the next element of the stack (or queue)
     *
     * Description: doubly linked list node structure
     * for stack, queues, LIFO, FIFO
     */
    typedef struct stack_s
    {
            int n;
            struct stack_s *prev;
            struct stack_s *next;
    } stack_t;

    /**
     * struct instruction_s - opcode and its function
     * @opcode: the opcode
     * @f: function to handle the opcode
     *
     * Description: opcode and its function
     * for stack, queues, LIFO, FIFO
     */
    typedef struct instruction_s
    {
            char *opcode;
            void (*f)(stack_t **stack, unsigned int line_number);
    } instruction_t;

Compilation & Output

Your code will be compiled this way:

    $ gcc -Wall -Werror -Wextra -pedantic -std=c89 *.c -o monty

Any output must be printed on stdout
Any error message must be printed on stderr
- Here is a link to a GitHub repository that could help you making sure your errors are printed on stderr

Tests

We strongly encourage you to work all together on a set of tests

The Monty language

Monty 0.98 is a scripting language that is first compiled into Monty byte codes (Just like Python). It relies on a unique stack, with specific instructions to manipulate it. The goal of this project is to create an interpreter for Monty ByteCodes files.

Monty byte code files

Files containing Monty byte codes usually have the .m extension. Most of the industry uses this standard but it is not required by the specification of the language. There is not more than one instruction per line. There can be any number of spaces before or after the opcode and its argument:

    julien@ubuntu:~/monty$ cat -e bytecodes/000.m
    push 0$
    push 1$
    push 2$
      push 3$
                       pall    $
    push 4$
        push 5    $
          push    6        $
    pall$
    julien@ubuntu:~/monty$

Monty byte code files can contain blank lines (empty or made of spaces only, and any additional text after the opcode or its required argument is not taken into account:

    julien@ubuntu:~/monty$ cat -e bytecodes/001.m
    push 0 Push 0 onto the stack$
    push 1 Push 1 onto the stack$
    $
    push 2$
      push 3$
                       pall    $
    $
    $
                               $
    push 4$
    $
        push 5    $
          push    6        $
    $
    pall This is the end of our program. Monty is awesome!$
    julien@ubuntu:~/monty$

The monty program

Usage: monty file
- where file is the path to the file containing Monty byte code
If the user does not give any file or more than one argument to your program, print the error message USAGE: monty file, followed by a new line, and exit with the status EXIT_FAILURE
If, for any reason, it’s not possible to open the file, print the error message Error: Can't open file <file>, followed by a new line, and exit with the status EXIT_FAILURE
- where <file> is the name of the file
If the file contains an invalid instruction, print the error message L<line_number>: unknown instruction <opcode>, followed by a new line, and exit with the status EXIT_FAILURE
- where is the line number where the instruction appears.
- Line numbers always start at 1
The monty program runs the bytecodes line by line and stop if either:
- it executed properly every line of the file
- it finds an error in the file
- an error occured
If you can’t malloc anymore, print the error message Error: malloc failed, followed by a new line, and exit with status EXIT_FAILURE.
You have to use malloc and free and are not allowed to use any other function from man malloc (realloc, calloc, …)

Quiz questions

Great! You've completed the quiz successfully! Keep going!

Question #0

Which of these stacks are keeping the order of insertion? (select all possible answers)

LILO
FIFO
LIFO
FILO

Question #1

What’s the command used to add a new element to a stack?

push
pop

Question #2

What’s the command used to remove a new element from a stack?

push
pop

Question #3

Which of these stacks are reversing the order of insertion? (select all possible answers)

LILO
FIFO
LIFO
FILO

Tasks

0. push, pall

mandatory

Implement the push and pall opcodes.

The push opcode

The opcode push pushes an element to the stack.

Usage: push <int>
- where <int> is an integer
if <int> is not an integer or if there is no argument given to push, print the error message L<line_number>: usage: push integer, followed by a new line, and exit with the status EXIT_FAILURE
- where is the line number in the file
You won’t have to deal with overflows. Use the atoi function

The pall opcode

The opcode pall prints all the values on the stack, starting from the top of the stack.

Usage pall
Format: see example
If the stack is empty, don’t print anything

    julien@ubuntu:~/monty$ cat -e bytecodes/00.m
    push 1$
    push 2$
    push 3$
    pall$
    julien@ubuntu:~/monty$ ./monty bytecodes/00.m
    3
    2
    1
    julien@ubuntu:~/monty$

Repo:

GitHub repository: monty

1. pint

mandatory

Implement the pint opcode.

The pint opcode

The opcode pint prints the value at the top of the stack, followed by a new line.

Usage: pint
If the stack is empty, print the error message L<line_number>: can't pint, stack empty, followed by a new line, and exit with the status EXIT_FAILURE

    julien@ubuntu:~/monty$ cat bytecodes/06.m 
    push 1
    pint
    push 2
    pint
    push 3
    pint
    julien@ubuntu:~/monty$ ./monty bytecodes/06.m 
    1
    2
    3
    julien@ubuntu:~/monty$

Repo:

GitHub repository: monty

2. pop

mandatory

Implement the pop opcode.

The pop opcode

The opcode pop removes the top element of the stack.

Usage: pop
If the stack is empty, print the error message L<line_number>: can't pop an empty stack, followed by a new line, and exit with the status EXIT_FAILURE

    julien@ubuntu:~/monty$ cat bytecodes/07.m 
    push 1
    push 2
    push 3
    pall
    pop
    pall
    pop
    pall
    pop
    pall
    julien@ubuntu:~/monty$ ./monty bytecodes/07.m 
    3
    2
    1
    2
    1
    1
    julien@ubuntu:~/monty$

Repo:

GitHub repository: monty

3. swap

mandatory

Implement the swap opcode.

The swap opcode

The opcode swap swaps the top two elements of the stack.

Usage: swap
If the stack contains less than two elements, print the error message L<line_number>: can't swap, stack too short, followed by a new line, and exit with the status EXIT_FAILURE

    julien@ubuntu:~/monty$ cat bytecodes/09.m 
    push 1
    push 2
    push 3
    pall
    swap
    pall
    julien@ubuntu:~/monty$ ./monty bytecodes/09.m 
    3
    2
    1
    2
    3
    1
    julien@ubuntu:~/monty$

Repo:

GitHub repository: monty

4. add

mandatory

Implement the add opcode.

The add opcode

The opcode add adds the top two elements of the stack.

Usage: add
If the stack contains less than two elements, print the error message L<line_number>: can't add, stack too short, followed by a new line, and exit with the status EXIT_FAILURE
The result is stored in the second top element of the stack, and the top element is removed, so that at the end:
- The top element of the stack contains the result
- The stack is one element shorter

    julien@ubuntu:~/monty$ cat bytecodes/12.m 
    push 1
    push 2
    push 3
    pall
    add
    pall
    
    julien@ubuntu:~/monty$ ./monty bytecodes/12.m 
    3
    2
    1
    5
    1
    julien@ubuntu:~/monty$

Repo:

GitHub repository: monty

5. nop

mandatory

Implement the nop opcode.

The nop opcode

The opcode nop doesn’t do anything.

Usage: nop

Repo:

GitHub repository: monty

6. sub

#advanced

Implement the sub opcode.

The sub opcode

The opcode sub subtracts the top element of the stack from the second top element of the stack.

Usage: sub
If the stack contains less than two elements, print the error message L<line_number>: can't sub, stack too short, followed by a new line, and exit with the status EXIT_FAILURE
The result is stored in the second top element of the stack, and the top element is removed, so that at the end:
- The top element of the stack contains the result
- The stack is one element shorter

    julien@ubuntu:~/monty$ cat bytecodes/19.m 
    push 1
    push 2
    push 10
    push 3
    sub
    pall
    julien@ubuntu:~/monty$ ./monty bytecodes/19.m 
    7
    2
    1
    julien@ubuntu:~/monty$

Repo:

GitHub repository: monty

7. div

#advanced

Implement the div opcode.

The div opcode

The opcode div divides the second top element of the stack by the top element of the stack.

Usage: div
If the stack contains less than two elements, print the error message L<line_number>: can't div, stack too short, followed by a new line, and exit with the status EXIT_FAILURE
The result is stored in the second top element of the stack, and the top element is removed, so that at the end:
- The top element of the stack contains the result
- The stack is one element shorter
If the top element of the stack is 0, print the error message L<line_number>: division by zero, followed by a new line, and exit with the status EXIT_FAILURE

Repo:

GitHub repository: monty

8. mul

#advanced

Implement the mul opcode.

The mul opcode

The opcode mul multiplies the second top element of the stack with the top element of the stack.

Usage: mul
If the stack contains less than two elements, print the error message L<line_number>: can't mul, stack too short, followed by a new line, and exit with the status EXIT_FAILURE
The result is stored in the second top element of the stack, and the top element is removed, so that at the end:
- The top element of the stack contains the result
- The stack is one element shorter

Repo:

GitHub repository: monty

9. mod

#advanced

Implement the mod opcode.

The mod opcode

The opcode mod computes the rest of the division of the second top element of the stack by the top element of the stack.

Usage: mod
If the stack contains less than two elements, print the error message L<line_number>: can't mod, stack too short, followed by a new line, and exit with the status EXIT_FAILURE
The result is stored in the second top element of the stack, and the top element is removed, so that at the end:
- The top element of the stack contains the result
- The stack is one element shorter
If the top element of the stack is 0, print the error message L<line_number>: division by zero, followed by a new line, and exit with the status EXIT_FAILURE

Repo:

GitHub repository: monty

10. comments

#advanced

Every good language comes with the capability of commenting. When the first non-space character of a line is #, treat this line as a comment (don’t do anything).

Repo:

GitHub repository: monty

11. pchar

#advanced

Implement the pchar opcode.

The pchar opcode

The opcode pchar prints the char at the top of the stack, followed by a new line.

Usage: pchar
The integer stored at the top of the stack is treated as the ascii value of the character to be printed
If the value is not in the ascii table (man ascii) print the error message L<line_number>: can't pchar, value out of range, followed by a new line, and exit with the status EXIT_FAILURE
If the stack is empty, print the error message L<line_number>: can't pchar, stack empty, followed by a new line, and exit with the status EXIT_FAILURE

    julien@ubuntu:~/monty$ cat bytecodes/28.m 
    push 72
    pchar
    julien@ubuntu:~/monty$ ./monty bytecodes/28.m 
    H
    julien@ubuntu:~/monty$

Repo:

GitHub repository: monty

12. pstr

#advanced

Implement the pstr opcode.

The pstr opcode

The opcode pstr prints the string starting at the top of the stack, followed by a new line.

Usage: pstr
The integer stored in each element of the stack is treated as the ascii value of the character to be printed
The string stops when either:
- the stack is over
- the value of the element is 0
- the value of the element is not in the ascii table
If the stack is empty, print only a new line

    julien@ubuntu:~/monty$ cat bytecodes/31.m 
    push 1
    push 2
    push 3
    push 4
    push 0
    push 110
    push 0
    push 108
    push 111
    push 111
    push 104
    push 99
    push 83
    pstr
    julien@ubuntu:~/monty$ ./monty bytecodes/31.m 
    School
    julien@ubuntu:~/monty$

Repo:

GitHub repository: monty

13. rotl

#advanced

Implement the rotl opcode.

The rotl opcode

The opcode rotl rotates the stack to the top.

Usage: rotl
The top element of the stack becomes the last one, and the second top element of the stack becomes the first one
rotl never fails

    julien@ubuntu:~/monty$ cat bytecodes/35.m 
    push 1
    push 2
    push 3
    push 4
    push 5
    push 6
    push 7
    push 8
    push 9
    push 0
    pall
    rotl
    pall
    julien@ubuntu:~/monty$ ./monty bytecodes/35.m 
    0
    9
    8
    7
    6
    5
    4
    3
    2
    1
    9
    8
    7
    6
    5
    4
    3
    2
    1
    0
    julien@ubuntu:~/monty$

Repo:

GitHub repository: monty

14. rotr

#advanced

Implement the rotr opcode.

The rotr opcode

The opcode rotr rotates the stack to the bottom.

Usage: rotr
The last element of the stack becomes the top element of the stack
rotr never fails

Repo:

GitHub repository: monty

15. stack, queue

#advanced

Implement the stack and queue opcodes.

The stack opcode

The opcode stack sets the format of the data to a stack (LIFO). This is the default behavior of the program.

Usage: stack

The queue opcode

The opcode queue sets the format of the data to a queue (FIFO).

Usage: queue

When switching mode:

The top of the stack becomes the front of the queue
The front of the queue becomes the top of the stack

    julien@ubuntu:~/monty$ cat bytecodes/47.m
    queue
    push 1
    push 2
    push 3
    pall
    stack
    push 4
    push 5
    push 6
    pall
    add
    pall
    queue
    push 11111
    add
    pall
    julien@ubuntu:~/monty$ ./monty bytecodes/47.m
    1
    2
    3
    6
    5
    4
    1
    2
    3
    11
    4
    1
    2
    3
    15
    1
    2
    3
    11111
    julien@ubuntu:~/monty$

Repo:

GitHub repository: monty

16. Brainf*ck

#advanced

Write a Brainf*ck script that prints School, followed by a new line.

All your Brainf*ck files should be stored inside the bf sub directory
You can install the bf interpreter to test your code: sudo apt-get install bf
Read: Brainf*ck

    julien@ubuntu:~/monty/bf$ bf 1000-school.bf 
    School
    julien@ubuntu:~/monty/bf$

Repo:

GitHub repository: monty
Directory: bf
File: 1000-school.bf

#advanced

Add two digits given by the user.

Read the two digits from stdin, add them, and print the result
The total of the two digits with be one digit-long (<10)

    julien@ubuntu:~/monty/bf$ bf ./1001-add.bf
    81
    9julien@ubuntu:~/monty/bf$

Repo:

GitHub repository: monty
Directory: bf
File: 1001-add.bf

18. Multiplication

#advanced

Multiply two digits given by the user.

Read the two digits from stdin, multiply them, and print the result
The result of the multiplication will be one digit-long (<10)

    julien@ubuntu:~/monty/bf$ bf 1002-mul.bf
    24
    8julien@ubuntu:~/monty/bf$

Repo:

GitHub repository: monty
Directory: bf
File: 1002-mul.bf

19. Multiplication level up

#advanced

Multiply two digits given by the user.

Read the two digits from stdin, multiply them, and print the result, followed by a new line

    julien@ubuntu:~/monty/bf$ bf 1003-mul.bf 
    77
    49
    julien@ubuntu:~/monty/bf$

Repo:

GitHub repository: monty
Directory: bf
File: 1003-mul.bf

Name		Name	Last commit message	Last commit date
Latest commit History 55 Commits
bf		bf
bytecodes		bytecodes
.monty.h.swp		.monty.h.swp
.stack.c.swp		.stack.c.swp
README.md		README.md
calc.c		calc.c
free_head.c		free_head.c
main.c		main.c
monty		monty
monty.h		monty.h
pchar.c		pchar.c
pstr.c		pstr.c
stack.c		stack.c
swap_nop.c		swap_nop.c

GideonBature/monty

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0x19. C - Stacks, Queues - LIFO, FIFO

Resources

Learning Objectives

General

Copyright - Plagiarism

Requirements

General

GitHub

More Info

Data structures

Compilation & Output

Tests

The Monty language

Quiz questions

Question #0

Question #1

Question #2

Question #3

Tasks

0. push, pall

1. pint

2. pop

3. swap

4. add

5. nop

6. sub

7. div

8. mul

9. mod

10. comments

11. pchar

12. pstr

13. rotl

14. rotr

15. stack, queue

16. Brainf*ck

18. Multiplication

19. Multiplication level up

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