Placeholders

Each character in a string can be accessed by the number of it's place in the string starting at 0. Huh? It works like this:

name= "Steve Jobs"
name[0] => "S"
name[4] => "e"
name[5] => " "
name[6] => "J"

Multiplying Strings

print (10 * 'a') 

Output is:
aaaaaaaaaa

• Allows the user to enter data from the keyboard.
• It waits for the user to press the Enter key before taking the information.
• Returns a string.

The basic syntax is:

input("string that is displayed to the user")

Let's take a look at an example:

school = input('Enter the name of your school:')
print("You go to", school)

The print() function displays information to the screen - it can display a combination of text and variables including adding separators.

Here's the basic syntax:

print(value1, value2, ...sep, end, file, flush)

A little more there then we initially learned. Here's what this all means:

Review of the Basics

print("Hello World!")

The print() function takes a string as its parameter. You can assign a value to variable and then print that variable. For example:

phrase = "Hello World"
print(phrase)

Concatenating (or "adding" two strings )

Can concatenate strings by putting a plus sign (+) between them. Either like this:

print("Hello World! " + "It is a beautiful day.")

Using Commas to Concatenate

Can concatenate strings with commas when you are using a print() function - faster to type & run.

print("Hello World!", "It is a beautiful day.")

Or use a mix of variables and straight text.

print("Hello World!", phrase2)

Separating Output

You can separate things by a new line so every item is on a new line.

first= "chocolate"
second = "gardening"
third ="hot bath"
print("Elizabeth\'s fav things are:", first, second, third, sep='\n')

This gives us this output:

Elizabeth's fav things are:
chocolate
gardening
hot bath

Ending Output

Similar to using separators between strings - this allows you to put something at the end of a string.

print("Today is a beautiful day", end='.')
print("Today is a beautiful day", end='!')

This gives us this output:

Today is a beautiful day.
Today is a beautiful day!

A condition is how we compare two things such as variables, numbers or strings. The comparison returns a value of True or False. In Python, the logical operators to compare two things are as follows:

Operator   Description
  ==       Equal To
  !=       Not Equal To
  >        Greater Than
  <        Less Than
  >=       Greater than or Equal to
  <=       Less than or Equal to
  in       Is a string contained within another string?

Now, we know how to check to see if a single condition is valid or not. But, often you are checking to see if multiple conditions are valid. For example, if it is Sunday and the weather is nice you can go swimming.

We use Boolean Operators to evaluate more than one condition.

Here are a few examples of comparing multiple conditions in Python code.

#Set a few variables
inches_snow = 6
still_snowing = True
temperature = 15

#Now compare the variables
print(inches_snow > 5 and temperature < 32)  =>  True
print(inches_snow > 15 and temperature < 32)  =>  False
print(inches_snow > 15 or temperature < 32)  =>  True
print(inches_snow > 5 or (still_snowing and temperature < 32)  =>  True
print(inches_snow > 5 and (not still_snowing and temperature < 32)  =>  False

Simple Examples

   inches_snow = int(input("How much snow did you get?"))
   if inches_snow > 5:
       print('No School Today')

   inches_snow = int(input("How much snow did you get?"))
   if inches_snow == 1:
       print('Go to school but wear boots')

   #example of using 'in'
   favorite_animal = “bobcat”
   if ‘cat’ in favorite_animal:
       print(‘You like cats!')

Booleans & None

Now, let's look at a few examples using booleans and the None value.

   #Using a boolean 
   still_snowing=True
   if still_snowing:
       print ("Woot!!!  Time to go sledding!! )

   #Let's see an example using the not 
   if not still_snowing:
       print ("Time to shovel... )

#Comment remember that 'None' is used when the variable is empty.
age = None
if age == None:
    print('You apparently have not been born yet!')

Full Example

inches_snow = int(input("How much snow did you get?"))
if inches_snow> 5 and inches_snow < 12:
    print('No School Today')
elif inches_snow >= 12 and inches_snow < 24:
    print('Obviously no school - go sledding!!!')
elif inches_snow >= 24:
    print('Can you even open your front door?') 
else:
    print('Ha! Get up, eat breakfast and get to school')
    print('I hope you didn't forget to do your homework!')