Comparison and logical operators¶
Definition¶
Comparison operators are used to compare two values and give a result of True or False.
Comparison operators¶
For the examples below, assume that a = 15
and b = 10
Symbol | Meaning | Example | Result |
---|---|---|---|
== |
Equal to | a == b |
False |
!= |
Not equal to | a != b |
True |
> |
Greater than | a > b |
True |
< |
Less than | a < b |
False |
>= |
Greater than or equal to | a >= b |
True |
<= |
Less than or equal to | a <= b |
False |
Logical operators¶
Logical operators will always result in a result of True or False. For the examples below, assume that a = True
and b = False
.
Symbol | Meaning | Example | Result |
---|---|---|---|
and |
Both expressions are True |
a and b |
False |
or |
At least one of the expressions is True |
a or b |
True |
not |
The expression is not True |
not a |
False |
Note
You can use brackets with comparison and logical operators. For example: not (a and b)
.
Easy example¶
a = 10
b = 15
if a == b:
print('The numbers are the same')
else:
print('The numbers are different')
Show/Hide Output
The numbers are different
Examples¶
Example 2 - Saving the result of a comparison to a variable¶
a = 20
b = 15
same = a == b
print(same)
Show/Hide Output
False
Example 3 - Using the result of a comparison in an IF statement¶
a = 20
b = 15
if a > b:
print('a is bigger than b')
else:
print('a is smaller than, or the same size as b')
Show/Hide Output
a is bigger than b
Example 4 - Using Boolean operators in an IF statement¶
level = 4
livesRemaining = 3
if livesRemaining > 0 and level <= 10:
print('Let\'s play')
Show/Hide Output
Let's play
Example 5 - Using comparison operators in a while statement¶
This program will print the current level and add one to the current level each time it loops.
level = 1
while level <= 5:
print('Current level: ' + level)
level = level + 1
Show/Hide Output
Current level: 1
Current level: 2
Current level: 3
Current level: 4
Current level: 5
Example 6 - Using a NOT statement¶
gameOver = False
if not gameOver:
print('Play Game')
else:
print('Game over')
Show/Hide Output
Play Game
Note
This could be written as if gameOver == False
but it is better written as above.
Example 7 - Multiple logical operators¶
gameOver = False
currentScore = 120
level = 7
if currentScore > 100 and level >= 5 and not gameOver:
print('You\'re doing really well')
else:
print('You must keep trying')
Show/Hide Output
You're doing really well
Key points¶
Warning
==
is used for comparisons and =
is used for assignment. So if a = b:
will not work, but this mistake can lead to an assignment happening when you actually want a comparison.