Python Conditions

Conditional Statements in Python

Conditional statements allow you to run specific blocks of code depending on whether a condition is true or false. They are essential for decision-making in programs.

Syntax of if Statements

The most basic conditional in Python is the if statement:

if condition:
    code_block

• condition: an expression that evaluates to True or False.
• code_block: runs only if the condition is true.

Basic Example

x = 10
if x > 5:
    print("x is greater than 5")

Output:

x is greater than 5

If the condition x > 5 is true, the message is printed.

Adding an else Clause

An else clause allows you to run code when the condition is false:

x = 3
if x > 5:
    print("x is greater than 5")
else:
    print("x is 5 or less")

Output:

x is 5 or less

Using elif (Else If)

The elif keyword lets you test multiple conditions in order:

x = 7
if x > 10:
    print("x is greater than 10")
elif x > 5:
    print("x is greater than 5 but 10 or less")
else:
    print("x is 5 or less")

Output:

x is greater than 5 but 10 or less

Python checks each condition from top to bottom. Once one is true, it runs the corresponding block and skips the rest.

Comparison Operators

You’ll often use these in conditions:

• ==: equal to
• !=: not equal to
• <: less than
• <=: less than or equal to
• >: greater than
• >=: greater than or equal to

Example:

x = 5
if x == 5:
    print("x is exactly 5")

Output:

x is exactly 5

Logical Operators

You can combine multiple conditions using:

• and: all conditions must be true
• or: at least one condition must be true
• not: inverts a condition

Example with and:

x = 8
if x > 5 and x < 10:
    print("x is between 6 and 9")

Output:

x is between 6 and 9

Example with or:

x = 3
if x < 2 or x > 4:
    print("x is outside the range 2–4")
else:
    print("x is between 2 and 4")

Output:

x is outside the range 2–4

Nested if Statements

You can place an if inside another if:

x = 12
if x > 10:
    if x < 20:
        print("x is between 11 and 19")

Output:

x is between 11 and 19

While nesting is allowed, it's better to keep logic flat when possible for readability.

Practical Example: Grading System

score = 85

if score >= 90:
    print("Grade: A")
elif score >= 80:
    print("Grade: B")
elif score >= 70:
    print("Grade: C")
else:
    print("Grade: D or lower")

Output:

Grade: B

Truthy and Falsy Values

In Python, certain values automatically evaluate as False:

• False
• None
• 0 (any numeric type)
• "" (empty string)
• [], {}, () (empty collections)

Everything else is considered True.

Example:

if []:
    print("List is not empty")
else:
    print("List is empty")

Output:

List is empty

Summary

• Use if, elif, and else to control program flow based on conditions.
• Comparison and logical operators help define complex conditions.
• Be aware of truthy and falsy values when testing variables.
• Keep logic readable—flatten conditions where possible.

Conditional statements are the foundation of decision-making in programming. Mastering them will make your programs more flexible and intelligent.