Decision Making in Python¶

Python provides several ways to make decisions in your code using conditional statements. The most common are if, if-else, elif, and nested conditions.

The if Statement¶

The if statement executes a block of code if a condition is true.

age = 18
if age >= 18:
    print("You are an adult.")

The if-else Statement¶

The if-else statement executes one block if the condition is true, and another if it’s false.

age = 16
if age >= 18:
    print("You are an adult.")
else:
    print("You are a minor.")

The elif Statement¶

The elif (else if) statement allows you to check multiple conditions.

score = 85
if score >= 90:
    print("Grade: A")
elif score >= 80:
    print("Grade: B")
elif score >= 70:
    print("Grade: C")
else:
    print("Grade: F")

Nested Conditions¶

You can nest if statements inside other if statements for more complex logic.

age = 25
has_license = True
if age >= 18:
    if has_license:
        print("You can drive.")
    else:
        print("You need a license.")
else:
    print("You are too young to drive.")

Comparison Operators¶

Common comparison operators used in conditions:

== : Equal to
!= : Not equal to
> : Greater than
< : Less than
>= : Greater than or equal to
<= : Less than or equal to

Logical Operators¶

Logical operators combine conditions:

and : Both conditions must be true
or : At least one condition must be true
not : Negates the condition

age = 20
has_ticket = True
if age >= 18 and has_ticket:
    print("You can enter the concert.")

match case¶

The match statement, introduced in Python 3.10, provides structural pattern matching, similar to switch-case in other languages but more powerful. It matches a value against patterns and executes the corresponding block.

n = 2
match n:
    case 0:
        print("Zero")
    case 1 | 2 | 3:
        print("Small number")
    case _:
        print("Large number")


# output: Small Number

Patterns can include literals, variables, sequences, and more for complex matching. Use case _ as a default catch-all. Note: if you have expression or complex condition, go with if-elif-else.