Requirements

General

Allowed editors: vi, vim, emacs

All your files will be compiled on Ubuntu 14.04 LTS

Your programs and functions will be compiled with gcc 4.8.4 using the flags -Wall -Werror -Wextra and -pedantic

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 are not allowed to use global variables

No more than 5 functions per file

You are not allowed to use the standard library. Any use of functions like printf, puts, etc… is forbidden

You are allowed to use _putchar

You don’t have to push _putchar.c, we will use our file. If you do it won’t be taken into account

In the following examples, the main.c files are shown as examples. You can use them to test your functions, but you don’t have to push them to your repo (if you do we won’t take them into account). We will use our own main.c files at compilation. Our main.c files might be different from the one shown in the examples

The prototypes of all your functions and the prototype of the function _putchar should be included in your header file called holberton.h

Don’t forget to push your header file

You are not allowed to use any kind of loops

You are not allowed to use static variables

Tasks

0. She locked away a secret, deep inside herself, something she once knew to be true... but chose to forget

File: 0-puts_recursion.c

Write 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.

julien@ubuntu:~/0x08. Recursion$ cat 0-main.c
#include "holberton.h"

/**
 * main - check the code for Holberton School students.
 *
 * Return: Always 0.
 */
int main(void)
{
    _puts_recursion("Betty Holberton");
    return (0);
}
julien@ubuntu:~/0x08. Recursion$ gcc -Wall -pedantic -Werror -Wextra _putchar.c 0-main.c 0-puts_recursion.c -o 0-puts_recursion
julien@ubuntu:~/0x08. Recursion$ ./0-puts_recursion 
Betty Holberton
julien@ubuntu:~/0x08. Recursion$

1. Why is it so important to dream? Because, in my dreams we are together

File: 1-print_rev_recursion.c

Write a function that prints a string in reverse.

Prototype: void _print_rev_recursion(char *s);

julien@ubuntu:~/0x08. Recursion$ cat 1-main.c
#include "holberton.h"

/**
 * main - check the code for Holberton School students.
 *
 * Return: Always 0.
 */
int main(void)
{
    _print_rev_recursion("\nColton Walker");
    return (0);
}
julien@ubuntu:~/0x08. Recursion$ gcc -Wall -pedantic -Werror -Wextra _putchar.c 1-main.c 1-print_rev_recursion.c -o 1-print_rev_recursion
julien@ubuntu:~/0x08. Recursion$ ./1-print_rev_recursion 
reklaW notloC
julien@ubuntu:~/0x08. Recursion$

2. Dreams feel real while we're in them. It's only when we wake up that we realize something was actually strange

File: 2-strlen_recursion.c

Write a function that returns the length of a string.

Prototype: int _strlen_recursion(char *s); FYI: The standard library provides a similar function: strlen. Run man strlen to learn more.

julien@ubuntu:~/0x08. Recursion$ cat 2-main.c 
#include "holberton.h"
#include <stdio.h>

/**
 * main - check the code for Holberton School students.
 *
 * Return: Always 0.
 */
int main(void)
{
    int n;

    n = _strlen_recursion("Corbin Coleman");
    printf("%d\n", n);
    return (0);
}
julien@ubuntu:~/0x08. Recursion$ gcc -Wall -pedantic -Werror -Wextra  2-main.c 2-strlen_recursion.c -o 2-strlen_recursion
julien@ubuntu:~/0x08. Recursion$ ./2-strlen_recursion 
14
julien@ubuntu:~/0x08. Recursion$

3. You mustn't be afraid to dream a little bigger, darling

File: 3-factorial.c

Write 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 an error
Factorial of 0 is 1

julien@ubuntu:~/0x08. Recursion$ cat 3-main.c
#include "holberton.h"
#include <stdio.h>

/**
 * main - check the code for Holberton School students.
 *
 * Return: Always 0.
 */
int main(void)
{
    int r;

    r = factorial(1);
    printf("%d\n", r);
    r = factorial(5);
    printf("%d\n", r);
    r = factorial(10);
    printf("%d\n", r);
    r = factorial(-1024);
    printf("%d\n", r);
    return (0);
}
julien@ubuntu:~/0x08. Recursion$ gcc -Wall -pedantic -Werror -Wextra 3-main.c 3-factorial.c -o 3-factorial
julien@ubuntu:~/0x08. Recursion$ ./3-factorial 
1
120
3628800
-1
julien@ubuntu:~/0x08. Recursion$

4. Once an idea has taken hold of the brain it's almost impossible to eradicate

File: 4-pow_recursion.c

Write 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.

julien@ubuntu:~/0x08. Recursion$ cat 4-main.c
#include "holberton.h"
#include <stdio.h>

/**
 * main - check the code for Holberton School students.
 *
 * Return: Always 0.
 */
int main(void)
{
    int r;

    r = _pow_recursion(1, 10);
    printf("%d\n", r);
    r = _pow_recursion(1024, 0);
    printf("%d\n", r);
    r = _pow_recursion(2, 16);
    printf("%d\n", r);
    r = _pow_recursion(5, 2);
    printf("%d\n", r);
    r = _pow_recursion(5, -2);
    printf("%d\n", r);
    r = _pow_recursion(-5, 3);
    printf("%d\n", r);
    return (0);
}
julien@ubuntu:~/0x08. Recursion$ gcc -Wall -pedantic -Werror -Wextra 4-main.c 4-pow_recursion.c -o 4-pow
julien@ubuntu:~/0x08. Recursion$ ./4-pow 
1
1
65536
25
-1
-125
julien@ubuntu:~/0x08. Recursion$

5. Your subconscious is looking for the dreamer

File: 5-sqrt_recursion.c

Write 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.

julien@ubuntu:~/0x08. Recursion$ cat 5-main.c 
#include "holberton.h"
#include <stdio.h>

/**
 * main - check the code for Holberton School students.
 *
 * Return: Always 0.
 */
int main(void)
{
    int r;

    r = _sqrt_recursion(1);
    printf("%d\n", r);
    r = _sqrt_recursion(1024);
    printf("%d\n", r);
    r = _sqrt_recursion(16);
    printf("%d\n", r);
    r = _sqrt_recursion(17);
    printf("%d\n", r);
    r = _sqrt_recursion(25);
    printf("%d\n", r);
    r = _sqrt_recursion(-1);
    printf("%d\n", r);
    return (0);
}
julien@ubuntu:~/0x08. gcc -Wall -pedantic -Werror -Wextra 5-main.c 5-sqrt_recursion.c -o 5-sqrt
julien@ubuntu:~/0x08. Recursion$ ./5-sqrt 
1
32
4
-1
5
-1
julien@ubuntu:~/0x08. Recursion$

6. Inception. Is it possible?

File: 6-is_prime_number.c

Write a function that returns 1 if the input integer is a prime number, otherwise return 0.

Prototype: int is_prime_number(int n);

julien@ubuntu:~/0x08. Recursion$ cat 6-main.c
#include "holberton.h"
#include <stdio.h>

/**
 * main - check the code for Holberton School students.
 *
 * Return: Always 0.
 */
int main(void)
{
    int r;

    r = is_prime_number(1);
    printf("%d\n", r);
    r = is_prime_number(1024);
    printf("%d\n", r);
    r = is_prime_number(16);
    printf("%d\n", r);
    r = is_prime_number(17);
    printf("%d\n", r);
    r = is_prime_number(25);
    printf("%d\n", r);
    r = is_prime_number(-1);
    printf("%d\n", r);
    r = is_prime_number(113);
    printf("%d\n", r);
    r = is_prime_number(7919);
    printf("%d\n", r);
    return (0);
}
julien@ubuntu:~/0x08. Recursion$ gcc -Wall -pedantic -Werror -Wextra 6-main.c 6-is_prime_number.c -o 6-prime
julien@ubuntu:~/0x08. Recursion$ ./6-prime 
0
0
0
1
0
0
1
1
julien@ubuntu:~/0x08. Recursion$

7. They say we only use a fraction of our brain's true potential. Now that's when we're awake. When we're asleep, we can do almost anything

File: 7-is_palindrome.c

Write a function that returns 1 if a string is a palindrome and 0 if not.

Prototype: int is_palindrome(char *s);
An empty string is a palindrome

julien@ubuntu:~/0x08. Recursion$ cat 7-main.c
#include "holberton.h"
#include <stdio.h>

/**
 * main - check the code for Holberton School students.
 *
 * Return: Always 0.
 */
int main(void)
{
    int r;

    r = is_palindrome("level");
    printf("%d\n", r);
    r = is_palindrome("redder");
    printf("%d\n", r);
    r = is_palindrome("holberton");
    printf("%d\n", r);
    r = is_palindrome("step on no pets");
    printf("%d\n", r);
    return (0);
}
julien@ubuntu:~/0x08. Recursion$ gcc -Wall -pedantic -Werror -Wextra 7-main.c 7-is_palindrome.c -o 7-palindrome
julien@ubuntu:~/0x08. Recursion$ ./7-palindrome 
1
1
0
1
julien@ubuntu:~/0x08. Recursion$