#!/usr/bin/env python
# coding: utf-8

# In[12]:


# Section 5.5 -- passing arguments to functions
#Definition: An argument is any data that you pass
#            to a function for usage in the function.
# Example: print("abc") -- "abc" is the argument of the print function
#
# Similar idea: a parameter of a function is a variable
#               local to that function that gets assigned
#               to an argument
#
# Both concepts are intimiately related. Just know the difference
# in their usage. 
#
# note: book calls parameters "parameter variables"
#
# 
# Example -- a doubling function
def show_double(number):
    result=2*number
    print("The double of",number,"is",result)
show_double(3)
show_double(1.5)
show_double("abc") # peculiar -- the action of "*2" on a string
#                  # behaves as doubling the string
#
#
# Example -- tripling function slightly modified
def main():
    value=5
    show_triple(value)
def show_triple(number):
    result=number*3
    print("The triple of",number,"is",result)
main()
    


# In[19]:


# This program will convert cups to fluid ounces
# write a function cups_to_ounces that takes an input
# integer number of cups and outputs the equivalent
# number of fluid ounces
def main():
    intro_message()
    # Get the number of cups from the user
    number_of_cups=int(input("How many cups do you want to convert?"))
    cups_to_ounces(number_of_cups)
def intro_message():
    print("This program converts cups to fluid ounces. For your info:")
    print("1 cup = 8 fluid ounces")
def cups_to_ounces(cups):
    total_ounces=cups*8
    print(cups,"cups is",total_ounces,"fluid ounces")
main()


# In[28]:


# Functions with multiple arguments
# Write a function that multiplies two numbers
def num_mult(num1,num2):
    result=num1*num2
    print(num1,"multiplied with",num2,"is",result)
num_mult(3,4)
num_mult(1.2,2)
num_mult(2,"abc") #<-- weird, Python interprets 
#                 # int*string as repeating string int times
# num_mult("abc","def") <-- gives an error -- Python does not
#                          # know how to interpret
#                          # string*string
#num_mult(2.0,"abc") #<-- error -- even though 2.0 can be 
#                    #typecast as string, Python doesn't do it
num_mult(int(2.0),"abc") #<-- works b/c I did the typecast
#
#
# First and last name program
first_name=input("What is your first name?")
last_name=input("What is your last name?")
def first_last(firstname,lastname):
    print("Your last name is",lastname,"your first name is",firstname)
first_last(first_name,last_name)


# In[34]:


# Keyword arguments
def main():
    show_interest(rate=0.01,periods=10,principal=10000)
    show_interest(0.01,10,10000)
    show_interest(10000,periods=10,rate=0.01)
    # show_interest(periods=10,10000,rate=0.01) <-- error b/c keyword arg came before pos. arg
def show_interest(principal,rate,periods):
    interest=rate*principal*periods
    print("The rate is",rate)
    print("The principal is",principal)
    print("The simple interest is $",format(interest,'.2f'),sep='')
main()

# general rule: can mix keyword arguments with non-keyword
# arguments, BUT all non-keyword arguments MUST come before
# all keyword arguments


# In[2]:


# Section 5.6 -- Global Variables and Global Constants
# Def: A global variable is one that can be accessed by all functions.
#
# Simple example
my_val=10 # this is a global variable because it can accessed
#         # from within the function showvalue() below
def showvalue(): 
    print("my_val is",my_val)
showvalue()

# There is a keyword global that can make a variable global.
def main():
    global number
    number=int(input("Give me an integer."))
    show_number()
def show_number():
    print("Your number is",number)
main()

# generally -- you want to avoid global variables
# as much as possible -- this is because they can make
# debugging difficult --- so avoid doing the above as much as possible

# Global constants are same idea -- usually they appear
# when you define magic numbers.
# MAX=4 <-- this is used throughout the code