Conditional Statements

Conditional statements allow a Python program to make decisions. Based on whether a condition is True or False, Python executes the appropriate block of code.

What is a Condition?

A condition is an expression that produces either True or False.

age = 25

print(age >= 18)

Output

True

Since the value of age is 25, the condition age >= 18 is true.

1. if Statement

The if statement executes a block of code only when the specified condition is true.

Syntax

if condition:
    statement

Notice the colon : after the condition. The statement inside the block must be indented.

Example

marks = 80

if marks >= 40:
    print("Student Passed")

Output

Student Passed

What Happens When the Condition is False?

If the condition is false, Python simply skips the code inside the if block.

marks = 30

if marks >= 40:
    print("Student Passed")

print("Program Completed")

Output

Program Completed

2. if-else Statement

The else block executes when the if condition is false.

Syntax

if condition:
    statement
else:
    statement

Example

marks = 35

if marks >= 40:
    print("Pass")
else:
    print("Fail")

Output

Fail

3. if-elif-else Statement

When a program needs to check multiple conditions, Python provides the elif keyword.

Syntax

if condition1:
    statement
elif condition2:
    statement
else:
    statement

Grade Example

marks = 82

if marks >= 90:
    print("Grade A+")
elif marks >= 75:
    print("Grade A")
elif marks >= 60:
    print("Grade B")
elif marks >= 40:
    print("Grade C")
else:
    print("Fail")

Output

Grade A

Python checks the conditions from top to bottom. Once it finds the first true condition, its block executes and the remaining conditions are skipped.

Multiple elif Conditions

You can use multiple elif blocks when the application has several possible outcomes.

temperature = 30

if temperature > 35:
    print("Very Hot")
elif temperature > 25:
    print("Warm")
elif temperature > 15:
    print("Cool")
else:
    print("Cold")

Output

Warm

Nested if Statements

An if statement placed inside another if statement is called a nested conditional statement.

Nested conditions are useful when a second decision depends on the result of the first decision.

age = 25
has_id = True

if age >= 18:

    if has_id:
        print("Entry Allowed")
    else:
        print("ID Required")

else:
    print("Entry Not Allowed")

Output

Entry Allowed

Conditions using Comparison Operators

Comparison operators are commonly used inside conditional statements.

Conditions using Logical Operators

Logical operators allow multiple conditions to be combined into a single expression.

Using and

age = 25
attendance = 85

if age >= 18 and attendance >= 75:
    print("Eligible")

Using or

day = "Sunday"

if day == "Saturday" or day == "Sunday":
    print("Weekend")

Using not

is_logged_in = False

if not is_logged_in:
    print("Please Login")

Conditions with Strings

Conditional statements can also compare strings.

username = "Samadhan"

if username == "Samadhan":
    print("Welcome Samadhan")
else:
    print("User Not Found")

Conditions using in

The in operator can check whether a value exists inside a collection or string.

course = "Python Full Stack"

if "Python" in course:
    print("Python course selected")

Conditions using Boolean Values

Boolean variables can be directly used in conditional statements.

is_active = True

if is_active:
    print("Account is Active")
else:
    print("Account is Inactive")

Short-Hand if

A simple one-line condition can sometimes be written on a single line.

age = 25

if age >= 18: print("Adult")

This style is suitable only for very simple statements. For larger logic, normal indentation is easier to read.

Conditional Expression

Python also supports a one-line conditional expression for simple choices.

age = 25

status = "Adult" if age >= 18 else "Minor"

print(status)

Output

Adult

Example: Course Eligibility 📩🤓

Suppose a student wants to join a course at CIIT Training Institute 🤓. The application can check the student's qualification and programming experience.

qualification = "Graduate"
experience = 1

if qualification == "Graduate" and experience >= 1:
    print("Eligible for Advanced Training")
elif qualification == "Graduate":
    print("Eligible for Beginner Training")
else:
    print("Please check eligibility requirements")

Output

Eligible for Advanced Training

Example: Login Check 📩🤓

Conditional statements are commonly used in login and authentication logic.

username = "sam"
password = "python123"

if username == "sam" and password == "python123":
    print("Login Successful")
else:
    print("Invalid Username or Password")

Output

Login Successful

Importance of Indentation

Python uses indentation to identify which statements belong to a conditional block.

marks = 80

if marks >= 40:
    print("Pass")
    print("Good Job")

Both statements are part of the if block because they have the same indentation level.

Common Mistakes

• Forgetting the colon : after if, elif, or else.
• Using = instead of == for comparison.
• Incorrect indentation inside the condition.
• Writing conditions in the wrong order.
• Creating unnecessarily complicated nested conditions.

Why Condition Order Matters

In an if-elif-else structure, Python checks conditions from top to bottom. Therefore, the order of conditions matters.

marks = 95

if marks >= 40:
    print("Pass")
elif marks >= 90:
    print("A+")

Output:

Pass

Here, marks >= 40 is already true, so Python executes that block and never reaches the elif. More specific conditions should generally be checked before broader conditions.

marks = int(input("Enter marks: "))

if marks >= 40:
    print("Pass")
else:
    print("Fail")

age = int(input("Enter age: "))

if age < 13:
    print("Child")
elif age < 20:
    print("Teenager")
elif age < 60:
    print("Adult")
else:
    print("Senior Citizen")

Enter age: 25
Adult