Course Content

Python Functions Tutorial

1. What is a Function in Python?

What Is Function?Challenge: Building Functions Arguments Return Value Function Body Built-in Functions

2. Positional and Optional Arguments

Positional Arguments Challenge: Positional Arguments Optional Arguments Challenge: Optional Arguments

3. Arbitrary Arguments

Arbitrary Arguments Arbitrary Keyword Arguments Combination of Positional and Optional Arguments

4. Function Return Value Specification

Single Return Value Multiple Return Values None Return Value Generator Functions Challenge: Traffic lights

5. Recursion and Lambda Functions

Recursion Challenge: Search Engine Lambda Functions Immediately Invoked Lambda Expression Writing Effective and Maintainable Functions

Recursion

Recursion in Python is when a function calls itself. It's a useful technique for solving complex problems by breaking them down into smaller parts. The key elements of recursion are the base case (the termination condition) and the recursive case (where the function calls itself).


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def print_message(message, times):
    if times > 0:
        print(message)
        print_message(message, times - 1)

# Function call
print_message("Hello, Recursion!", 3)

Let's go step by step through how this recursive program works:

Condition Check: if times > 0, the function proceeds. In this case, times = 3, so the condition is true;
Print Message: the function prints "Hello, Recursion!";
Recursive Call: the function calls itself with times - 1;
Repetition: this process continues until times equals 0;
Termination: when the condition times > 0 is no longer true, the recursion stops, and the program completes.

Result: The message "Hello, Recursion!" is printed three times.

Task

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Complete the code for recursively generating passwords. The password should be random and consist of letters (both uppercase and lowercase) and digits. The function should generate the specified number of passwords, each having a certain length. Fill in the blanks (___) in the code:

Password Length Check: in the first blank, check if the length of the current password (current_password) has reached the specified length (length). If it has, print the password and move on to generate the next one.
Recursive Call: in the second blank, call the generate_passwords function with updated parameters, decreasing the password count by 1 (count - 1).

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Section 5. Chapter 1

Recursion


              1234567
            
def print_message(message, times):
    if times > 0:
        print(message)
        print_message(message, times - 1)

# Function call
print_message("Hello, Recursion!", 3)

Let's go step by step through how this recursive program works:

Condition Check: if times > 0, the function proceeds. In this case, times = 3, so the condition is true;
Print Message: the function prints "Hello, Recursion!";
Recursive Call: the function calls itself with times - 1;
Repetition: this process continues until times equals 0;
Termination: when the condition times > 0 is no longer true, the recursion stops, and the program completes.

Result: The message "Hello, Recursion!" is printed three times.

Task

Swipe to show code editor

Password Length Check: in the first blank, check if the length of the current password (current_password) has reached the specified length (length). If it has, print the password and move on to generate the next one.
Recursive Call: in the second blank, call the generate_passwords function with updated parameters, decreasing the password count by 1 (count - 1).

Switch to desktop for real-world practiceContinue from where you are using one of the options below

Everything was clear?

Thanks for your feedback!

Section 5. Chapter 1

Switch to desktop for real-world practiceContinue from where you are using one of the options below