## 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:

Functionality:

• 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).

Syntax:

Python

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.

Examples:

1. Generate numbers from 0 to 4 :

Python

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:

Python

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):

Python

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.
Python
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.
Python
if number % 2 == 0:
print("Number is even.")
else:
print("Number is odd.")

• if-elif-else statements: Handle multiple conditions in a sequential manner.
Python
print("Excellent")
print("Very Good")
print("Good")
else:
print("Needs improvement")

Types of Loops

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

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

Examples of Conditional Statements and Loops Combined

1. Finding even numbers in a list:
Python
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:
Python
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")
else:
for i in range(1, num + 1):
factorial *= i
print("Factorial of", num, "is", factorial)

3. Guessing game:
Python
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!")
else:
print("You guessed it in", guesses, "tries!")
break

Tips

• 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!

Sources