a few exercises to learn how to write interactive programs

user_input.py

# Python 2.7

# code examples and explanations from Python Crash Course by Eric Matthes

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# echo.py

# A simple program to have the computer take input from the user... Or so it seems!

message = ("Tell me something, and I will repeat it back to you: ")
print(message)

# Now, the message is printed, but the user cannot type anyhting in!
# What function do we need to add and where?

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# greetings.py

# So, The input() function, or raw_input() takes one argument: the prompt
# or instructions, that we want to display to the user so they know what to do.

# Argument = a piece of information passed from a function call to a function

# NOTE: Though this is originally written in 2.7, I will refer to raw_input() as input()

# IMPORTNANT: WRITE CLEAR PROMPTS!
# Each time you use the input() function, you should include a clear, easy-to-follow
# prompt that tells the user exactly what kind of inforamtion you're looking for.

# Write a program that asks for the user's name, then have the
# exact name they typed in return to the user.

##################################################
##################################################

####name = raw_input("Please enter your name: ")
####print("Hello, " + name + "!")

# Sometimes you'll want to write a longer prompt, perhaps more than one line
# For example, you might want to tell the user why you're asking for certain input

# You can store your prompt in a variable and pass that variable to the input() function
# This allows you to build your prompt over several lines,
# then write a clean input() statement
# Remember, think of a statement as a complete thought

prompt = "If you tell us who you are, we can create a unique message for you to see."
prompt += "\nWhat is your first name? "

# the operator += adds the new string to the end of the sting value from the line above

# what do we need to put on this line to actually take the input from the user?!
print("\nHello, " + name + "!")

# This example shows another way to build a multi-line string.
# The first line stores the first part of the message in the variable, prompt
# In the next line, the operator, += takes the string that was stored in prompt
# and adds the new string onto the end

# As you can see, the prompt now spans two lines, with a space after the question mark for clarity.

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# age.py
# Making comparisions with user input

# Python 2.7

# When you use the input() function, Python interprets everything the user enters
# as a string. Consider the next interpreter session, where the computer asks for the user's age:

age = raw_input("How old are you? ")
print(age)

# This seems fine at first, but Python returns the string representation
# of the number entered by the user

# We can fix this by using the int() function, which tells Python to treat
# the input as a numerical value.
# The int() function converts a string representation of a number to a numerical representation

# FIGURE OUT WHERE TO PUT THE int() FUNCTION!!!

age = raw_input("How old are you? ")
age = (age)         # Hint: change this line to age = int(age) to convert the string to a whole number
print(age >= 18)    # if you try this in the interpreter, omit the print() function

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# theme_park.py

# Let's use the int() function in another program
# Imagine you are ready to ride some big roller coasters at a theme park!
# Have you ever had your height checked, to see if you are tall enough to ride a certain rollercoaster?
# Write a program that determines whether a person is tall enough
# to ride a certain roller coaster:

height = raw_input("How tall are you, in inches? ")
height = int(height)

# NOW, PUT THE CONDITION STATMENTS BELOW!
# To help you get started...
if height