Adventures in Machine Learning

IF ELIF and ELSE Statements in Python: Mastering Conditional Constructs

IF, ELIF, and ELSE in PythonPython is a programming language that is widely used for different applications ranging from data analysis to web development. One essential aspect of Python programming is its conditional statements, which determine whether a particular condition is true or false.

The conditional statements in Python are written using IF, ELIF, and ELSE. In this article, we will explore the different types of conditional statements in Python and their examples.

Example 1: IF and ELSE

The IF and ELSE statements are the most basic form of conditional statements in Python. The “IF” statement evaluates an expression and determines whether it is true or false.

If it is true, the code block following the “IF” statement is executed, and if it is false, the code block following the “ELSE” statement is executed. A typical use case of the IF and ELSE statements is when determining senior discount eligibility.

For example, suppose you are writing a program for a store that offers senior discounts. The eligibility for the discount is based on the customer’s age, and seniors are those who are 60 or above.

The code snippet below shows how you can use the IF and ELSE statements to determine a customer’s eligibility for the discount. “`

age = int(input(“Enter your age: “))

if age >= 60:

print(“Congratulations! You qualify for the senior discount.”)

else:

print(“Sorry, you do not qualify for the senior discount.”)

“`

Example 2: IF, ELIF, and ELSE

In some instances, you may need to evaluate multiple conditions in a single program.

The IF, ELIF, and ELSE statements provide a way to do this. The ELIF statement is short for “else if” and enables you to test multiple conditions, one after the other.

A typical use case of the IF, ELIF, and ELSE statements is when determining junior discount eligibility with additional conditions. For example, suppose you are writing a program for a store that offers junior discounts to customers who are between 18 and 21 years old and have a valid student ID.

The code snippet below shows how you can use the IF, ELIF, and ELSE statements to determine a customer’s eligibility for the discount. “`

age = int(input(“Enter your age: “))

student_id = input(“Do you have a valid student ID?

(Y/N): “)

if age >= 18 and age <= 21 and student_id == 'Y':

print(“Congratulations! You qualify for the junior discount.”)

elif age >= 18 and age <= 21 and student_id == 'N':

print(“Sorry, you need a valid student ID to qualify for the junior discount.”)

else:

print(“Sorry, you do not qualify for the junior discount.”)

“`

Example 3: IF, ELIF, and ELSE with input() function

The input() function in Python allows the user to enter values from the console while the program is running. This function makes programs more user-friendly and provides greater flexibility.

The IF, ELIF, and ELSE statements can be combined with the input() function to make the program even more interactive. For example, suppose you are writing a program that prompts the user to enter a number and determines whether the number is positive, negative, or zero.

The code snippet below shows how you can use the IF, ELIF, and ELSE statements with the input() function to accomplish this. “`

num = int(input(“Enter a number: “))

if num > 0:

print(“The number is positive.”)

elif num < 0:

print(“The number is negative.”)

else:

print(“The number is zero.”)

“`

Example 4: Nested IF

Nested IF statements are useful when more complex conditions need to be evaluated.

A nested IF is an IF statement that appears inside another IF statement. The nested IF statement is evaluated only if the outer IF statement is true.

A typical use case of nested IF is when determining senior discount eligibility based on membership. For example, suppose you are writing a program for a store that offers senior discounts to customers who are 60 years or older and have been members for five or more years.

The code snippet below shows how you can use nested IF statements to determine whether a customer qualifies for the discount. “`

age = int(input(“Enter your age: “))

membership_years = int(input(“Enter the number of years you’ve been a member: “))

if age >= 60:

if membership_years >= 5:

print(“Congratulations! You qualify for the senior discount.”)

else:

print(“Sorry, you need to be a member for at least five years to qualify for the senior discount.”)

else:

print(“Sorry, you do not qualify for the senior discount.”)

“`

Conclusion

In conclusion, the IF, ELIF, and ELSE statements are powerful constructs in Python that allow programmers to create sophisticated conditional statements with ease. By combining these statements with other Python functions such as input(), nested IF statements, and more, programmers can create interactive, flexible, and powerful programs.

Python’s IF, ELIF, and ELSE statements provide a powerful mechanism for creating complex and flexible conditional statements used in various applications, including data analysis and web development. The article explored four types of conditional statements- generic, multiple conditions, input function, and nested IF- with examples and keywords of each.

These constructs enable programmers to write interactive programs that make user experience more profound. Ultimately, the article highlights the importance of understanding and mastering conditional constructs in Python programming.

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