If Statements

Narrated by Tilda,

self-taught developer

So far we've:

  • Created Expressions
  • Used Variables
  • Made Our Own Functions

Next Step:

  • Write code that will only run on a certain condition
  • For example, only display "Game Over" when we've run out of lives

The "If" Statement

  • Also called a "conditional" statement
  • Allows the computer to decide what code to run based on a condition

Basic Comparisons

Flowcharts

Flowcharts

# Basic comparisons
if a < b:
    print("a is less than b")

if a > b:
    print("a is greater than b")

print("Done")

More Comparison Types

if a ≤ b:

Indentation

Using And/Or

Boolean Variables

George Boole

(1815 - 1864)

Credited for Boolean Algebra

The "input" Function

"Else" and "Else If"

Text Comparisons

Multiple Text Possibilities

Case-Insensitive Comparisons

Review

# If statements

if a < b:
    print("a is less than b")
# If statements

if a < b:
    print("a is less than b")
elif a > b:
    print("a is greater than b")
else:
    print("a is equal to be")
# Assignment operator uses one equals
# You are TELLING it the value
a = 5

# Comparison operator uses two equals
# You are ASKING if it is the value
if a == 5:
     print("a is five")
# Boolean values store True or False
is_rainy = True

# If statements can operate on these
if is_rainy:
     print("Open umbrella")
    
if not is_rainy:
     print("Water garden")