# 4.3. Comparisons#

Boolean values most often arise from comparison operators. Python includes a variety of operators that compare values. For example, 3 is larger than 1 + 1.

3 > 1 + 1

True


The value True indicates that the comparison is valid; Python has confirmed this simple fact about the relationship between 3 and 1+1. The full set of common comparison operators are listed below.

Comparison

Operator

True example

False Example

Less than

<

2 < 3

2 < 2

Greater than

>

3>2

3>3

Less than or equal

<=

2 <= 2

3 <= 2

Greater or equal

>=

3 >= 3

2 >= 3

Equal

==

3 == 3

3 == 2

Not equal

!=

3 != 2

2 != 2

An expression can contain multiple comparisons, and they all must hold in order for the whole expression to be True. For example, we can express that 1+1 is between 1 and 3 using the following expression.

1 < 1 + 1 < 3

True


The average of two numbers is always between the smaller number and the larger number. We express this relationship for the numbers x and y below. You can try different values of x and y to confirm this relationship.

x = 12
y = 5
min(x, y) <= (x+y)/2 <= max(x, y)

True


Strings can also be compared, and their order is alphabetical. A shorter string is less than a longer string that begins with the shorter string.

"Dog" > "Catastrophe" > "Cat"

True