More Advanced Comparisons - Code in Context, Computing & the Liberal Arts

Complex Conditional Statements¶

We can imagine programming scenarios in which we want to compare more than two values or evaluate multiple conditions as part of a conditional statement. We can do this using logical operators and complex conditional statements.

For example, 5 < 6 > 7 evaluates whether 5 is less than 6 and 6 is greater than 7. This statement would return False.

An example using strings: "apple" > "banana" < "blueberry" evaluates whether "apple" is greater than (or comes after) "banana" and whether "banana" is less than (or comes before) "blueberry". This statement would return False.

Python examples:

# an example that compares three integers
print(5 < 6 > 7) # returns false because 6 is not greater than 7

# an example that compares three strings
print("apple" > "banana" < "blueberry") # returns false because apple comes before or is less than banana

Logical Operators¶

We can also compare or relate multiple conditions using logical operators: and, or, not

Definition

“A logical operator is a symbol or word used to connect two or more expressions such that the value of the compound expression produced depends only on that of the original expressions and on the meaning of the operator. Common logical operators include AND, OR, and NOT.” (Busbee and Braunschweig, “Logical Operators”)

For example, 5 < 6 and 6 < 7 evaluates whether 5 < 6 and 6 < 7 are true. This statement would return True.

Another example: 5 < 6 or 6 > 7 evaluates whether 5 < 6 or 6 > 7 is true. This statement would return True.

Logical operators in Python:

Name	Syntax	Example	Description
And	`and`	`x == y and y != z`	Returns `True` if both statements are true
Or	`or`	`x != y or y == z`	Returns `True` if one of the statements is true
Not	`not`	`not(x == y and y != z)`	Reverses the result, returns `False` if the result is true

# example using logical operators
print(5 < 6 and 6 < 7) # returns true because both statements are true

print(5 < 6 or 6 > 7) # returns true because at least one statement is true

print(not(5 < 6 and 6 < 7)) # returns false, inverse of initial true

Additional Resources

For more on logical operators in Python: W3Schools, Python Logical Operators

Comprehension Check¶

Logical Operators & Complex Conditional Statements Comprehension Check

Application¶

Q13: Write a program that uses Python’s comparison operators (==, !=, >, <, >=, <=) to compare at least three (3) numeric values. Answer to this question includes program + comments that document process and explain your code.

Outline for this program:

# first numeric value

# second numeric value

# third numeric value

# complex comparison statement

Q14: Write a program that uses Python’s comparison operators (==, !=, >, <, >=, <=) to compare at least three (3) string objects. Answer to this question includes program + comments that document process and explain your code.

Outline for this program:

# first string object

# second string object

# third string object

# complex comparison statement