Intro to Python
Learn Python

Conditionals

This section covers:
Boolean expressions
Logical operators
If/else statements

Boolean Expressions

In the previous section, we learned what an expression is. Boolean expressions are expressions that evaluate to a boolean value - either true or false.

We’ve already seen an example of boolean expressions: comparing 2 numbers.
10 > 0
is a boolean expression that uses the
>
comparison operator to check if 10 is greater than 0. Other comparison operators are
<
(less than),
==
(equals),
!=
(not equals).

Logical Operators

Python has 3 logical operators:
and
,
or
, and
not
. Like all Python operators, these perform operations on expressions. Specifically, they can only be used on boolean expressions, and using a logical operator will result in a boolean value.
and
is True if both expressions are True
or
is True if one or both expressions are True
not
is True if the expression is False (it does a reversal)

4 > 5 and 6 != 10 # evaluates to False
4 < 5 and 6 != 10 # evaluates to True
4 > 5 or 6 != 10 # evaluates to True
not 4 > 5 # evaluates to True

If/else Statements

If/else statements
let you tell the program how to make decisions. Every if/else statement has a boolean expression as its
condition
.

if number_of_points >= 10:
print("You win!")
else:
print("You still need more points")

Task
Status
1
Learn about booleans
Not Started
2
Learn about logical operators
Not Started
3
Learn about if/else statements
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