This document contains a series of exercises designed to build your confidence and skill in handling command-line arguments in C. Each exercise focuses on a common pattern you might encounter in 42 School exams and other C programming challenges.

Goal: To become proficient in parsing, validating, and using the argc and argv parameters.

Tools Allowed: For these exercises, restrict yourself to the write function from <unistd.h> for all output. You may use <stdlib.h> for atoi where specified.

Objective: Write a program that prints the number of arguments it received.

File: arg_count.c

Logic:

1. The program should take any number of arguments.
2. It should print a single digit character representing the number of arguments (including the program name).
3. Follow the output with a newline character.

Hint: argc is an integer. To print it with write, you must convert it to a character. For single digits, you can do this by adding the ASCII value of '0'.

Example Usage:

$> ./arg_count
1
$> ./arg_count hello world
3
$> ./arg_count "one arg"
2

Objective: Write a program that prints each argument on a new line.

File: print_args.c

Logic:

1. The program should iterate through the argv array.
2. For each string in argv (starting from argv[1]), print the string to the console.
3. Each argument should be followed by a newline character.
4. If there are no arguments (other than the program name), the program should print nothing.

Hint: You will need a function to calculate the length of a string to use write correctly.

Example Usage:

$> ./print_args See you later alligator
See
you
later
alligator
$> ./print_args
$>

Objective: Write a program that prints the arguments in reverse order.

File: rev_args.c

Logic:

1. This is similar to "Print Arguments," but you should iterate through argv backwards.
2. Start from the last argument (argv[argc - 1]) and go down to argv[1].
3. Print each argument, followed by a newline.

Example Usage:

$> ./rev_args See you later alligator
alligator
later
you
See

Objective: Recreate a basic version of the echo command that supports the -n flag to suppress the trailing newline.

File: my_echo.c

Logic:

1. Check if the first argument (argv[1]) is exactly "-n".
2. If it is, print all subsequent arguments (argv[2], argv[3], etc.), separated by a single space. Do not print a final newline.
3. If the first argument is not "-n", print all arguments (argv[1], argv[2], etc.), separated by a single space, and then print a final newline.

Example Usage:

$> ./my_echo hello world
hello world
$> ./my_echo -n hello world
hello world$> # Note the lack of a newline
$> ./my_echo -n
$>
$> ./my_echo

Good luck! Completing these will give you a strong foundation for more complex problems like do_op, search_and_replace, and even ft_split.