0x08-recursion

0x08. C - Recursion

Resource

• 0x08. Recursion, introduction
• What on Earth is Recursion?
• C - Recursion
• C Programming Tutorial 85, Recursion pt.1
• C Programming Tutorial 86, Recursion pt.2

Tasks

• All *-main.c files will be located in the main directory.

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0. She locked away a secret, deep inside herself, something she once knew to be true... but chose to forget : A function that prints a string, followed by a new line.
   • Prototype: void _puts_recursion(char *s);
   • FYI: The standard library provides a similar function: puts. Run man puts to learn more.
   • Compile the code this way: gcc -Wall -pedantic -Werror -Wextra -std=gnu89 _putchar.c main/0-main.c 0-puts_recursion.c -o 0-puts_recursion
1. Why is it so important to dream? Because, in my dreams we are together : A function that prints a string in reverse.
   • Prototype: void _print_rev_recursion(char *s);
   • Compile the code this way: gcc -Wall -pedantic -Werror -Wextra -std=gnu89 _putchar.c main/1-main.c 1-print_rev_recursion.c -o 1-print_rev_recursion
2. Dreams feel real while we're in them. It's only when we wake up that we realize something was actually strange
   • Prototype: int _strlen_recursion(char *s);
   • FYI: The standard library provides a similar function: strlen. Run man strlen to learn more.
   • Compile the code this way: gcc -Wall -pedantic -Werror -Wextra -std=gnu89 main/2-main.c 2-strlen_recursion.c -o 2-strlen_recursion
3. You mustn't be afraid to dream a little bigger, darling : A function that returns the factorial of a given number.
   • Prototype: int factorial(int n);
   • If n is lower than 0, the function should return -1 to indicate error.
   • Factorial of 0 is 1.
   • Compile the code this way: gcc -Wall -pedantic -Werror -Wextra -std=gnu89 main/3-main.c 3-factorial.c -o 3-factorial
4. Once an idea has taken hold of the brain it's almost impossible to eradicate : A function that returns the value of x raised to the power of y.
   • Prototype: int _pow_recursion(int x, int y);
   • If y is lower than 0, the function should return -1
   • FYI: The standard library provides a different function: pow. Run man pow to learn more.
   • Compile the code this way: gcc -Wall -pedantic -Werror -Wextra -std=gnu89 main/4-main.c 4-pow_recursion.c -o 4-pow
5. Your subconscious is looking for the dreamer : A function that returns the natural square root of a number.
   • Prototype: int _sqrt_recursion(int n);
   • If n does not have a natural square root, the function should return -1
   • FYI: The standard library provides a different function: sqrt. Run man sqrt to learn more.
   • Compile the code this way: gcc -Wall -pedantic -Werror -Wextra -std=gnu89 main/5-main.c 5-sqrt_recursion.c -o 5-sqrt