The famous factorials (aula de introdução a programação)

factorial.c

#include <stdio.h>
#include <stdlib.h>

int main(int argc, char *argv[])
{
    printf("%i\n", factorial(atoi(argv[1])));
}

int factorial(int number)
{
    int result = 1;

    while(number > 1){
        result = result * number;
        number = number - 1;
    }

    return result;
}

factorial_recursion.c

#include <stdio.h>
#include <stdlib.h>

int main(int argc, char *argv[])
{
    printf("%i\n", factorial(atoi(argv[1])));
}

int factorial(int number)
{
    if(number <= 1)
        return 1;
    else
        return  number * factorial(number - 1);
}

ruby_factorial.rb

class Integer
  def factorial
    if self == 0
      1
    else
      self * (self - 1).factorial
    end
  end
end

puts ARGV[0].to_i.factorial

ruby_factorial_inject.rb

# Adeus stack overflow

class Integer
  def factorial
    1.upto(self).inject(1){ |result, current_number| result * current_number }
  end
end

puts ARGV[0].to_i.factorial