Friday 8 March 2024

range() function in Python 18


The range() function in Python is a powerful tool for generating sequences of numbers. Here's a breakdown of how it works and some examples to illustrate its usage:


  • range() generates a sequence of integers.

  • By default, it starts from 0, increments by 1, and stops before a specified end value (which is not included).



range(start, stop, step)

  • start (optional): This argument defines the starting number of the sequence. If omitted, it defaults to 0.

  • stop (required): This argument specifies the number before which the sequence stops. It's not included in the sequence itself.

  • step (optional): This argument defines the increment between each number in the sequence. By default, it's 1. You can use a positive or negative step value to control the direction of the sequence.


  1. Generate numbers from 0 to 4 :


numbers = range(5)
print(list(numbers))  # Output: [0, 1, 2, 3,4]

  1. Generate numbers from 1 to 10 (excluding 10) with a step of 2:


numbers = range(1, 11, 2)
print(list(numbers))  # Output: [1, 3, 5, 7, 9]

  1. Generate numbers in descending order from 5 to 1 (excluding 0):


numbers = range(5, 0, -1)
print(list(numbers))  # Output: [5, 4, 3, 2, 1]

Key Points:

  • range() itself doesn't store the actual numbers. It's an iterable object that generates numbers on demand when used in a loop or converted to a list using list().

  • The stop value is exclusive, meaning the sequence won't include that number.

I hope this explanation clarifies the range() function in Python! Feel free to ask if you have any more questions.

Types of Conditional Statements

  • if statements: Execute code blocks based on whether a condition is True.
    if age >= 18:
        print("You are eligible to vote.")

  • if-else statements: Execute one code block if a condition is True, otherwise execute a different code block.
    if number % 2 == 0:
        print("Number is even.")
        print("Number is odd.")   

  • if-elif-else statements: Handle multiple conditions in a sequential manner.
    grade = 85
    if grade >= 90:
    elif grade >= 80:
        print("Very Good")
    elif grade >= 70:
        print("Needs improvement")

Types of Loops

  • for loops: Iterate over a sequence (list, string, tuple, etc.)
    colors = ["red", "blue", "green"]
    for color in colors:

  • while loops: Continue looping until a condition is no longer True.
    count = 0
    while count < 5:
        print("Count:", count)
        count += 1

Examples of Conditional Statements and Loops Combined

  1. Finding even numbers in a list:
    numbers = [1, 5, 8, 22, 13, 4]
    for num in numbers:
        if num % 2 == 0:
            print(num, "is even")

  2. Calculating factorial with user input:
    num = int(input("Enter a number: "))
    factorial = 1

    if num < 0:
        print("Factorial doesn't exist for negative numbers")
    elif num == 0:
        print("Factorial of 0 is 1")
        for i in range(1, num + 1):
            factorial *= i
        print("Factorial of", num, "is", factorial)

  3. Guessing game:
    import random
    secret_number = random.randint(1, 20)

    for guesses in range(1, 7):
        guess = int(input("Guess a number between 1 and 20: "))
        if guess < secret_number:
            print("Too low!")
        elif guess > secret_number:
            print("Too high!")
            print("You guessed it in", guesses, "tries!")


  • Pay attention to indentation. Incorrect indentation breaks code functionality.

  • Use meaningful variable names to enhance code readability.

Let me know if you'd like to explore more specific scenarios or problem types!



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