Lecture7 # Conditional Statements (if/else)

Conditional statements, such as if and else statements, are fundamental building blocks of programming that allow you to make decisions in your code based on certain conditions. In Python, these statements help control the flow of your program by executing different code blocks depending on whether specific conditions are true or false.

Here's a beginner-friendly guide to understanding if and else statements in Python:

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The if Statement

The if statement is used to test a condition. If the condition evaluates to True, the code block inside the if statement is executed. If the condition is False, the code block is skipped. Here's the basic structure:

if condition:
    # Code to be executed if the condition is True

Example:

age = 18

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

In this example, if the age is greater than or equal to 18, the message "You are an adult." will be printed.

The else Statement

The else statement is used in conjunction with an if statement to provide an alternative code block to execute when the if condition is False. Here's how it works:

if condition:
    # Code to be executed if the condition is True
else:
    # Code to be executed if the condition is False

Example:

age = 15

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

In this example, if the age is less than 18, the message "You are a minor." will be printed because the condition in the if statement is False.

The elif Statement

The elif statement (short for "else if") allows you to test multiple conditions in sequence. It's used when you have more than two possible outcomes. Here's how it works:

if condition1:
    # Code to be executed if condition1 is True
elif condition2:
    # Code to be executed if condition2 is True
else:
    # Code to be executed if neither condition1 nor condition2 is True

Example:

grade = 85

if grade >= 90:
    print("A")
elif grade >= 80:
    print("B")
elif grade >= 70:
    print("C")
else:
    print("D")

In this example, the program evaluates the grade and prints the corresponding letter grade based on the conditions.

Conclusion

Conditional statements (if, else, elif) are essential for controlling the flow of your Python programs. They allow your code to make decisions based on conditions, making your programs more dynamic and responsive to different scenarios. As you gain more experience in Python programming, you'll find that conditional statements are used extensively in many applications and algorithms.