Python if statement

The if statement in Python is used to execute a block of code only when a specified condition is True. It is the foundation for decision-making in Python programs, allowing the program to respond dynamically based on conditions.

Example 

temperature = 30

if temperature > 25:

    print("It's a hot day!")

Output:

It's a hot day!

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Syntax

if condition:

    # Code to execute if the condition is True

• condition: A statement that evaluates to True or False.

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Why Use if?

1. Dynamic Decisions: Enables programs to behave differently based on specific conditions.
2. User Interaction: Processes user inputs and makes decisions accordingly.
3. Core Logic: Forms the basis for building complex program logic.

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Common Examples

1. Checking Even or Odd

number = 7

if number % 2 == 0:

    print("Even number")

else:

    print("Odd number")

Output:

Odd number

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2. Age Check

age = 16

if age >= 18:

    print("You can vote.")

else:

    print("You are not eligible to vote.")

Output:

You are not eligible to vote.

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3. Grading System

marks = 82

if marks >= 90:

    print("Grade: A")

elif marks >= 75:

    print("Grade: B")

else:

    print("Grade: C")

Output:

Grade: B

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4. Nested if Example

num = 12

if num > 0:

    if num % 3 == 0:

        print("Positive and divisible by 3")

Output:

Positive and divisible by 3

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Key Notes

• Conditions can involve comparison (>, <, ==, etc.) and logical operators (and, or, not).
• Always use proper indentation to define the code block.
• Combine if, elif, and else to handle multiple conditions effectively.

This structure ensures you have a definition, an example immediately following, the syntax, why use it, and other common examples for clarity.