42 Piscine

My solutions to the exercises of the 42 Rio Piscine, the intensive selection bootcamp of the 42 Network.

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About

The Piscine is the admission process of the 42 schools: four weeks of full-time, peer-to-peer learning with no teachers and no lectures. Candidates start from zero and work through daily modules covering the Unix shell and the C language, with exams and group projects along the way.

This repository holds the work I did during my Piscine. It is where I wrote my first lines of C.

Contents

Module	Topic	Exercises
shell01	Shell scripting: find, awk, tr, id, ifconfig	5
C00	Output with write, loops and conditions	6
C01	Pointers and basic arrays	8
C02	String copying, checking and case conversion	9
C03	String comparison, concatenation and search	5
C04	String length, printing strings and numbers	3
C05	Math: iteration vs. recursion	7
C06	Program arguments (argc / argv)	3
C07	Dynamic memory allocation with malloc	4
rush00	Weekend group project: drawing rectangles	5 patterns

Full exercise list

shell01

Ex	File	Description
01	print_groups.sh	Lists the groups of the user in $FT_USER, separated by commas
02	find_sh.sh	Finds every .sh file and prints its name without the extension
03	count_files.sh	Counts files and directories from the current directory down
04	MAC.sh	Prints the machine's MAC addresses
06	skip.sh	Prints every other line of ls -l

C00

Ex	Function	Description
00	ft_putchar	Prints a character
01	ft_print_alphabet	Prints the alphabet in lowercase
02	ft_print_reverse_alphabet	Prints the alphabet in reverse
03	ft_print_numbers	Prints the digits 0–9
04	ft_is_negative	Prints N or P depending on the sign of a number
05	ft_print_comb	Prints every combination of three different digits in ascending order

C01

Ex	Function	Description
00	ft_ft	Sets an int to 42 through a pointer
01	ft_ultimate_ft	Same, through nine levels of pointers
02	ft_swap	Swaps two integers
03	ft_div_mod	Stores the quotient and remainder of a division
04	ft_ultimate_div_mod	Same, storing the results in the operands
05	ft_putstr	Prints a string
06	ft_strlen	Returns the length of a string
07	ft_rev_int_tab	Reverses an array of integers

C02

Ex	Function	Description
00	ft_strcpy	Copies a string
01	ft_strncpy	Copies up to n characters
02	ft_str_is_alpha	Checks if a string is only letters
03	ft_str_is_numeric	Checks if a string is only digits
04	ft_str_is_lowercase	Checks if a string is only lowercase letters
05	ft_str_is_uppercase	Checks if a string is only uppercase letters
06	ft_str_is_printable	Checks if a string is only printable characters
07	ft_strupcase	Converts a string to uppercase
08	ft_strlowcase	Converts a string to lowercase

C03

Ex	Function	Description
00	ft_strcmp	Compares two strings
01	ft_strncmp	Compares up to n characters
02	ft_strcat	Appends one string to another
03	ft_strncat	Appends up to n characters
04	ft_strstr	Finds a substring inside a string

C04

Ex	Function	Description
00	ft_strlen	Returns the length of a string
01	ft_putstr	Prints a string
02	ft_putnbr	Prints an integer

C05

Ex	Function	Description
00	ft_iterative_factorial	Factorial using a loop
01	ft_recursive_factorial	Factorial using recursion
02	ft_iterative_power	Power using a loop
03	ft_recursive_power	Power using recursion
04	ft_fibonacci	n-th Fibonacci number, recursively
05	ft_sqrt	Integer square root, or 0 if it is not exact
06	ft_is_prime	Checks if a number is prime

C06

Ex	Program	Description
00	ft_print_program_name	Prints the program's own name
01	ft_print_params	Prints the arguments, one per line
02	ft_rev_params	Prints the arguments in reverse order

C07

Ex	Function	Description
00	ft_strdup	Duplicates a string into newly allocated memory
01	ft_range	Returns an array with all integers between min and max
02	ft_ultimate_range	Same, through a pointer, returning the size
03	ft_strjoin	Joins an array of strings with a separator

Rush 00

The first weekend group project of the Piscine. The goal is to write a function rush(x, y) that draws a rectangle of width x and height y on the terminal, using a specific set of characters for corners and edges. The subject is available in rush00/rush00.pdf.

• rush00/ex00 – the assigned pattern (rush01)
• rush00/Bonus – the other four patterns (rush00, rush02, rush03, rush04)

Example, rush(5, 3) with the rush01 pattern:

/***\
*   *
\***/

Usage

Clone the repository:

git clone https://github.com/hadamas/42-piscine.git
cd 42-piscine

C exercises – each file is self-contained and starts with a comment describing the exercise. Compile with the flags used at 42:

cc -Wall -Wextra -Werror C00/ex05/ft_print_comb.c -o ft_print_comb
./ft_print_comb

Some files have their main function commented out, since only the function itself is submitted for evaluation. Uncomment it to test.

Rush – compile all files of a pattern together. Change the values passed to rush() in main.c to draw other sizes:

cc -Wall -Wextra -Werror rush00/ex00/*.c -o rush
./rush

Shell scripts

sh shell01/ex02/find_sh.sh
FT_USER=$(whoami) sh shell01/ex01/print_groups.sh

Piscine rules

Part of the challenge is the set of constraints every exercise must follow:

• Norminette – 42's strict coding standard: functions of at most 25 lines, at most 80 columns, no for loops, no switch, declarations at the top of the function
• Restricted functions – each exercise lists the only library functions allowed, often just write or malloc; everything else has to be written by hand
• Peer evaluation – every submission is reviewed by other candidates and by an automated grader

What I learned

• Navigating and automating tasks in a Unix shell
• The foundations of C: types, loops, pointers, strings and arrays
• Recursion and manual memory management
• Reading a specification carefully and handling edge cases
• Working and learning with peers, under time pressure

Author

Alanis Hadama (ahadama-) – 42 Rio GitHub: @hadamas

Looking for what came next? See so_long, a 2D game I built in the 42 Common Core.

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_{These solutions are shared for reference. If you are doing the Piscine, try the exercises on your own first; that is the whole point.}