Computer Science @ Kellenberg

Conditionals are what allow our programs to make decisions. Conditionals are generally based on evaluating items that are:

Operator	Meaning
<	Less Than
>	Greater Than
==	Equal To
!=	Not Equal To
>=	Greater than or equal to
<=	Less than or equal to

An example may be a program that determines if a user is old enough to vote by asking the user their age. If the user is 18 or older, then that user can vote.

#Ask the user their age
YourAge=input(“What is your age? “)

#Convert users age to an integer to evaluate numerically
IYourAge=int(YourAge)

#if statement -> Conditional!
if (IYourAge>17):
     print(“You are old enough to vote!”)
else:
     print(“Sorry, you can’t vote yet!”)

if Statement

The if statement is used to evaluate conditions and take action base on whether the condition evaluates to true or false.

if (Condition To Evaluate):
#Do This is true —>All items indented under if are executed until next
#De-Dent

if / else

An if / else statement lets the programmer create a conditional that does one thing if the condition evaluates to true and another if the condition evaluates to false.

if (Condition to Evaluate):
#Do this if true
else:
#Do this if false

if / elif / else

if / elif / else allows the programmer to evaluate multiple conditions. For example, assigning letter grades to numeric values may use if / elif / else:

#Assign letter grades
if (grade>95):
     LetterGrade="A+"
elif (grade>90):
     LetterGrade="A"
elif (grade>85):
     LetterGrade="B+"
elif (grade>79):
     LetterGrade="B"
elif (grade>69):
     LetterGrade="C"
elif (grade>64):
     LetterGrade="D"
else:
     LetterGrade="F"