Intro to
Programming
(with Python)

"""                                                                                       
 factorial.py       
 Looking at functions, doctests, and test-driven deveopment.
"""

def factorial(n):
    """ Return the factorial of n, i.e. n!, which is n * (n-1) * ... 2 * 1                
        >>> factorial(2)                                                                  
        2                                                                                 
        >>> factorial(5)                                                                  
        120                                                                               
    """                           
    return 0        # This is the wrong result. Tests will fail.

def main():
    print "-- factorial --"
    n = int(input("What is n? (i.e. 5) "))
    print("{}! is {}.".format(n, factorial(n)))

if __name__ == "__main__":
    import doctest
    doctest.testmod()
    main()

# Version 1 : what will be printed ?

name = "Jim"

def f():
  name = "Joe"
  return 1

def main():
  x = f()
  print(" name is {}".format(name))

main()

# Version 2 : what will be printed ?

names = ["Jim", "John", "Mary"]

def f():
  names[0] = "Joe"
  return 1

def main():
  x = f()
  print(" names is {}".format(names))

main()

def f1(x):
    print(x)

def f2():
    x = input(" ? ")
    return x

def f3(x):
    return x

y1 = f1(3)
print("y1 is '{}'".format(y1))

y2 = f2()
print("y2 is '{}'".format(y2))

y3 = f3(20)
print("y3 is '{}'".format(y3))

print("x is '{}'".format(x))